Co-factor activated recombinant adenovirus proteinases

ABSTRACT

This application describes methods and expression constructs for producing activatable recombinant adenovirus proteinases. Purified activatable recombinant adenovirus proteinases and methods of purification are described. Activated adenovirus proteinases and methods for obtaining activated adenovirus proteinases are further included. Isolated peptide cofactors of adenovirus proteinase activity, methods of purifying and identifying said peptide cofactors are also described. Antibodies immunoreactive with adenovirus proteinases, immunospecific antibodies, and methods for preparing them are also described. Other related methods and materials are also described.

GOVERNMENT SUPPORT

This invention was made with Government support under control numberDE-AC02-76CH00016, between the U.S. Department of Energy and AssociatedUniversities, Inc. The Government has certain rights in the invention.

RELATED APPLICATION

This application is a continuation-in-part of U.S. Ser. No. 07/851,217,filed Mar. 13, 1992, which is a continuation-in-part of U.S. Ser. No.07/545,585, filed Jun. 29, 1990, the disclosures of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

Adenoviruses have a double-stranded, linear DNA genome of about 36 kb.Adenovirus particles are nonenveloped, icosahedral structures composedof multiple copies of each of twelve virus-encoded proteins and a singlecopy of the DNA genome. Adenoviruses for many different eukaryoticspecies have been identified. All adenoviruses have a similar genomeorganization and virion structure, but adenoviruses from one species donot productively infect the cells of another species. ("TheAdenoviruses" Ginsberg, ed, New York: Plenum Press, 1984).

The most extensively studied adenoviruses are the human adenoviruses. Atleast 46 distinct human adenovirus serotypes have been described. Theseare classified into six subgroups (A-F) on the basis of relatedbiological and physical properties. The most extensively studied humanserotypes are types 2 and 5, which belong to subgroup C. Adenovirus type2 (Ad2) and type 5 (Ad5) are very closely related; the proteins of Ad2and Ad5 typically differ at only a few amino acid residues. Adenovirus12 belongs to subgroup A. Subgroup A adenoviruses differ sufficientlyfrom subgroup C viruses in that corresponding gene products of Ad2normally will not substitute for the Ad12 product, and vice versa.

All adenovirus genomes are believed to encode closely relatedproteinases (also called proteases and here, also appropriately calledendoproteinases), which cleave several virion precursor polypeptidesduring virion maturation (Krausslich et al., Ann. Rev. Biochem.7:701-754 (1988)). The adenovirus endoproteinase (EP) is assembled intovirions, with only a few copies in each virion. The adenovirus 2 (Ad2)endoproteinase has been shown to cleave six of the twelve proteins fromwhich virions are assembled. The mature virion components resulting fromthese six precursors have been designated IIIa, VI, VII (major coreprotein), VIII, Mu, and TP (terminal protein) (Anderson et al., Virology172:506-512 (1989)). (The full-length initial products of translationare designated with a p prefix; the C-terminal products ofendoproteolytic cleavage are designated by a -c suffix.) Precursorprocessing occurs primarily, if not exclusively, in young, fullyassembled virions (Ishibashi et al., Virology 57:409-424 (1974); Lewiset al., Cold Spring Harbor Symp. Quant. Biol. 39:581-590 (1974)). It hasbeen suggested that the endoproteinase is itself processedautocatalytically (Chatterjee et al., Proc. Natl. Acad. Sci. USA84:714-718 (1987)).

The 23 kilodalton (kDa)Ad2 EP is encoded by a gene that is expressed atlate times after virus infection. The endoproteinase gene is locatedwithin the L3 family of adenovirus genes. Evidence that the L3 23 kDaopen reading frame encodes an endoproteinase was first provided byanalysis of the temperature-sensitive Ad2 mutant, H2ts1 (Weber, J.Virol. 17:462-471 (1976)). The H2ts1 mutation changes proline codon 137of the L3 23 kDa reading frame to a leucine codon (Yeh-Kai et al., J.Mol. Biol. 167:217-222 (1983)). At the non-permissive temperature,virions produced in H2ts1-infected cells assemble efficiently, butcontain precursors in place of the mature components found in wild typeparticles. Such immature virions attach to cells but fail to yieldproductive infections (Hannan et al., Intervirology 19:213-223 (1983);Mirza et al., Intervirology 13:307-311 (1980)).

Only a few copies of the adenovirus proteinase are present in eachvirion. As a consequence of the difficulty of obtaining sufficientquantities of this protein from its natural source, the proteinasepolypeptide had not been isolated, its enzymatic activity is not fullycharacterized, nor is the role of the proteinase in virion maturationwell understood.

SUMMARY OF THE INVENTION

This invention relates to activatable adenovirus proteinases which, incombination with two cofactors, are activated adenovirus proteinases.The two cofactors, a polyanion cofactor and a short peptide cofactor,have been shown to be necessary complements of adenovirus proteinaseactivity. Activated adenovirus proteinases and peptide cofactors ofadenovirus proteinase activity are included. The present inventionfurther relates to methods for obtaining and purifying activatablerecombinant adenovirus proteinases, activated adenovirus proteinases,and peptide cofactors of adenovirus proteinase activity. Expressionconstructs suitable for expressing activatable recombinant adenovirusproteinases in host cells are further included. This invention furtherprovides antibodies which react specifically with adenovirus proteinasesand not with other adenovirus or mammalian cell proteins. Relatedmethods of use, including methods of interfering with activation of theactivatable proteinase, are also the subject of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B relate to a restriction site map of two Ad2 proteinaseexpression plasmids; FIG. 1A is the restriction site map of pT7AD23K5;FIG 1B is the restriction site map of pT7AD23K8. The approximatepositions of the human Ad2 proteinase reading frame, the β-lactamasegene (bla), and the E. coli origin of replication (ori), and thedirection of transcription from the T7 gene 10 promoter (φ10) areindicated.

FIG. 2 shows the segment of pT7AD23K5 encoding the junction of the OmpTsignal peptide sequence and the human Ad2 proteinase. The signalprocessing site at the arrow indicates the aminoterminus of theprocessed 23K5 fusion protein.

FIG. 3 shows the expression of recombinant Ad2 proteinases 23K5 and 23K6in E. coli after IPTG induction. Left: SDS-polyacrylamide gel stainedwith Coomassie Blue. Right: Autoradiogram of the pulse-labeled proteins.

FIG. 4 is an autoradiogram of an Ad2 proteinase assay experiment.

FIG. 5 is a chromatogram of tryptic peptide fractions of 23K6.

FIG. 6 shows the peptide sequence analysis of 23K6. Underliningindicates confirmed sequence.

FIGS. 7A and 7B relate to monitoring of proteinase activity. FIG. 7A isa pET expression plasmid pT7HEP1DBP (also referred to as pT7HIS2) which,upon induction, produces an artificial proteinase substrate calledHEP1DBP. FIG. 7B shows the results of fluorescence assays of proteinaseactivity: (A) wild type Ad2 virus; (B) H2ts1 virus; (C) purifiedrecombinant Ad2 proteinase; and (D) H2ts1 virus with proteinase. Thechange in fluorescence, AF, is the magnitude of the fluorescence fromthe sample minus the magnitude of the fluorescence from an identicalsolution without enzyme.

FIG. 8 shows the effect of DNase and Ad2 DNA on cofactor activity inH2ts1 virus: (A) DNase-treated H2ts1 virus; (B) H2ts1 treated withinactivated DNase; (C) untreated H2ts1 virus; and (D) no H2ts1 virus.Dark and open bars indicate without and with addition of Ad2 DNA,respectively.

FIG. 9 shows the effect of plasmin on cofactor activity in H2ts1 virus:(A) untreated H2ts1 virus; (B) plasmin-treated H2ts1 virus; and (C)H2ts1 virus treated with inactivated plasmin.

FIG. 10 shows purification of the peptide cofactor by filtration inCentricon-30.

FIG. 11A shows the elution profile from the reverse phase column. Arrowsindicate peaks containing peptide cofactor activity.

FIG. 11B shows the proteinase activity obtained in fluorescence assaysof the fractions in each peak.

FIG. 12 shows the sequences of the peptide cofactor in peaks a, b, and cand of the precursor to the Ad2 virion component VI (pVI). The locationsof the proteinase recognition sequences and of the peptide cofactorsequence in the pVI sequence are indicated by underlining and boldprint, respectively.

FIG. 13 shows reconstitution of proteinase activity in vitro withpurified components: (A) Titration of the pVI-c peptide cofactor; (B)Titration of Ad2 DNA.

FIG. 14 shows the Western blot analysis of virion-derived andrecombinant Ad2 proteinases:

A) Coomassie Blue-stained SDS-polyacrylamide gel:

B) Autoradiogram of the Western blot.

FIG. 15 shows Western blots of virion-derived and recombinant Ad2proteinases reacted with preimmune and α23K1 sera.

FIGS. 16A and 16B show the predicted amino acid sequences of severaladenovirus type proteinases.

FIG. 17 shows the detection of adenovirus proteinase in radiolabeledvirions.

FIG. 18 shows the location of adenovirus proteinase in Ad2 virions.

FIG. 19 shows (A) the map of pT7HEP1DBP, an expression vector for anartificial adenovirus substrate and (B) the segment of pT7HEP1DBPencoding the 17-amino acid HEP1DBP leader.

FIG. 20 (2 sheets) shows the nucleotide sequence of the region encodingAd12 pMu and pVI.

DEPOSIT

A strain of DH-1 containing the plasmid pT7AD23K6 was deposited underthe terms of the Budapest Treaty on the International Recognition of theDeposit of Microorganisms for the Purposes of Patent Procedure at theAmerican Type Culture Collection (Rockville, Md.), and given theAccession Number 68322. All restrictions on the availability to thepublic of the deposited material will be irrevocably removed upon thegranting of a patent.

DETAILED DESCRIPTION OF THE INVENTION

This invention provides preparations of activated adenovirus proteinaseswhich consist of an activatable recombinant adenovirus proteinase, a DNAcofactor and a peptide cofactor. The peptide cofactor is a shortpeptide, generally 11 amino acids long, and has an amino acid sequencewhich is substantially the same as that of the 11 amino acidcarboxy-terminus of the precursor to adenovirus virion component VI(pVI). The polyanion cofactor can consist of any DNA, single-stranded ordouble-stranded, including genomic, viral, cloned or syntheticoligomeric DNA. RNA, polyglutamic acid, polyaspartic acid and heparinalso satisfy the requirement for a polyanion. The activatable adenovirusproteinase can be a recombinant gene product, produced by expression ofa construct containing the coding sequence of an adenovirus proteinaseinserted into an expression vector which is appropriate for the hostcell. As described herein, recombinant adenovirus proteinases expressedin nonmammalian and mammalian host cells fold into activatableproteinases. As also described herein, in the presence of the twomentioned cofactors, the activatable proteinases become activatedadenovirus proteinases, which are also the subject of the presentinvention. The subject invention also includes methods for producing andpurifying activatable recombinant adenovirus proteinases from hostcells, expression constructs useful for producing activatable adenovirusproteinases, and purified activatable recombinant adenovirus proteinasesare provided. This invention further includes antibodies (monoclonal andpolyclonal) which recognize adenovirus proteinases, antibodies whichreact specifically with adenovirus proteinases but not with otheradenovirus or mammalian cell proteins, and methods of preparing theseantibodies. Methods relating to the use of the above materials are alsoincluded.

Described below is the production of activatable recombinant adenovirusproteinases in E. coli cells using constructs based on the pET series ofbacterial expression vectors (Rosenberg et al., Gene 56:125-135 (1988)).Production of activatable recombinant proteinase in cultured Sf9 insect(ATCC CRL 1711) cells using a baculovirus vector is also described. Asdescribed, activatable recombinant proteinases from two differentadenovirus subclasses have been produced (human adenovirus type 2 andtype 12) in E. coli. The methods of production and expression constructsused, as well as purification methods, are described. The recombinantproteins produced as described herein have been characterized, andphysical and functional characteristics are described. In particular,two cofactors necessary for activation of activatable recombinantadenovirus proteinases have been identified and characterized. Theiridentification makes it possible to interfere with the activity ofadenovirus proteinases, through inhibition of the activity of thecofactors. Preparation and characterization of an anti-proteinaseantibody are also described. Uses of the above-mentioned methods andmaterials are then discussed.

Bacterial Expression Constructs

Several plasmids suitable for expressing recombinant adenovirus type 2(Ad2) and type 12 (Ad12) proteinases in bacterial cells wereconstructed, as summarized in Table 2. As described in Example 2, theplasmids were constructed such that the coding sequences for theadenovirus proteinases were inserted in the expression cassette of abacterial expression vector, pET-12.

The pET-12 bacterial expression vector is a derivative of the pET-3expression vector. The pET-3 vector contains an origin of replication(ori) for maintenance of the plasmids in E. coli and the β-lactamase(bla) gene for selection of transformed cells by ampicillin resistance(see e.g., FIG. 1). The pET-3 vector also contains an expressioncassette based on transcription from the strong promoter (φ10) of gene10, which encodes the major capsid protein of bacteriophage T7. Thecassette further includes a ribosome binding site or Shine-Dalgarnosequence (AAGGAG; termed SD), the gene 10 translational start site, atranscription terminator, and unique restriction enzyme sites forinsertion of foreign genes into the cassette. In the plasmids describedbelow, the adenovirus proteinase reading frames are inserted into thepET expression cassettes such that the proteinase initiation codon is atthe correct distance (about 10 bp) from the ribosome recognition sitefor efficient protein synthesis. In pET vectors, the inserted foreigngene is expressed efficiently only when the T7 RNA polymerase is alsoexpressed in the host cell into which the pET vector is introduced. Whenprotein synthesis is desired, expression plasmids are used to transforman expressing strain, such as BL21(DE3). This strain has the T7 RNApolymerase gene integrated into its bacterial chromosome, under theIPTG-inducible lacUV5 promoter.

The pET-12 expression vector includes, in addition to the expressionelements described above, a leader sequence encoding the signal peptidesequence of the E. coli outer membrane protein T (OmpT). The vector wasdesigned to express the product of an inserted foreign gene as an OmpTfusion protein. A fusion protein containing the OmpT signal peptidesequence is expected to be transported through the E. coli plasmamembrane and into the bacterial periplasm. In the process, the OmpTsignal peptide is cleaved from the fusion protein by the E. coli signalpeptidase. The signal processing site falls between alanine₂₁ andserine₂₂ of the leader sequence. As a result, cleavage at the signalprocessing site of OmpT-proteinase fusion proteins, such as theexpression products of pT7AD23K5 and pT7AD23K15, leaves three aminoacids (Ser-Thr-His) of the signal peptide sequence at the aminoterminusof the proteinase (FIG. 2).

The prototype plasmid for expressing activatable Ad2 proteinase inbacteria is pT7AD23K6. Plasmid pT7AD23K6 contains the 204 codons of theAd2 proteinase reading frame plus a translational termination codon(TAA). The nucleotide and predicted amino acid sequences of the Ad2proteinase are shown in the Sequence Listing (SEQ ID NO: 1 and NO: 2).

pT7AD23K6 was derived from the plasmid pT7AD23K5 which encodes anOmpT-Ad2 proteinase fusion protein (FIG. 2). pT7AD23K6 differs frompT7AD23K5 in that it lacks the NdeI fragment containing the OmpT leadersequence (FIG. 2; see SEQ ID NO: 3), and thus, does not encode a proteinwith a signal peptide sequence.

Plasmid pT7AD23K8 (5226 bp) is a derivative of pT7AD23K6 [Anderson, C.W., Virology, 177;259 (1990)] and also expresses the wild-type 204-aminoacid EP polypeptide, but the DNA sequence (TTGAAA) corresponding tocodons 200 (Leu) and 201 (Lys) of the proteinase gene [Roberts, R. J. etal., Adenovirus DNA: The Viral Genome and Its Expression (W. Doerfler,Ed.) 1-51 (1986)] in pT7AD23K6 was altered to introduce a unique AflIIrestriction site (C|TTAAG) without changing the EP protein sequence. Theanti-sense strand EP carboxy-terminal oligonucleotide primer,5'-CTTGGATCCATTATTTTTACATGTTCTTAAGGTGACAA-3' (SEQ ID NO: 26), and thesense strand T7 promoter sequence primer, 5'-TAATACGACTCACTATAGGGAGA-3'(SEQ ID NO: 25), were used to copy the EP gene of pT7AD23K6. Theanti-sense primer has sequences corresponding to BamHI and AflIIrestriction sites (underlined); the BamHI site in the PCR product liesjust after the position of the natural TAA termination codon in the Ad2proteinase gene. After amplification, the NdeI (CA|TATG) and BamHI(G|GATCC)-cleaved PCR product was ligated with similarly cleaved pET-3CDNA to produce pT7AD23K8.

Both pT7AD23K8 and pT7AD23K10 differ from pT7AD23K6 in that adenovirussequences 3' of the termination codon, which are not important forproteinase expression in E. coli, were removed, and a terminator for T7polymerase transcription was placed in these plasmids to reduceexcessive expression of the bla ampicillin-resistance gene (see FIG. 1).

pT7AD23K11 and pT7AD23K13 encode variants of the Ad2 proteinase.pT7AD23K11.encodes a deletion mutant missing the nine amino acids, Glu₅-Gln-Glu-Leu-Lys-Ala-Ile-Val-Lys₁₃ (see SEQ ID NO: 2), of the wild typeAd2 proteinase.

Plasmid pT7AD23K13 (5253 bp) is a derivative of pT7AD23K8 that expressesthe wild-type Ad2 proteinase sequence with a 9-amino acid extension,-GHHHHHHNM (SEQ ID NO: 4), at the carboxy terminus. The oligonucleotides5'-TTAAGAACATGGGTCACCACCACCATCACCATAACATGTAAAAAT-3' (sense strand; SEQID NO: 27) and 5'-GATCCATTATTTTTACATGTTATGGTGATGGTGGTGGTGACCCATGTTC-3'(anti-sense strand; SEQ ID NO: 28), when annealed, form the requiredextension sequence with overlapping ends that are compatible with AflIIand BamHI cleavage sites. The annealed oligonucleotides were ligatedwith AflII and BamHI-cleaved pT7AD23K8 DNA to produce pT7AD23K13. Aunique BstEII cleavage site (G|GTNACC; underlined), occurs in pT7AD23K13at the beginning of the sequence that encodes the oligohistidine track.

Plasmids pT7AD23K15 and pT7AD23K16 are analogous to pT7AD23K5 andpT7AD23K6 [Anderson, C. W., Virology, 177;259 (1990)] except that theyexpress the Ad12 EP polypeptide [Houde, A. and Weber, J. M., NucleicAcids Res., 16;7195 (1988)]. The nucleotide and predicted amino acidsequences of the Ad12 proteinase are shown in the Sequence Listing (SEQID NO: 5 and NO: 6). The Ad12 EP gene was amplified with oligonucleotideprimers 5'-CCCGTCGACCCATATGGGTTCAAGC-3' (sense strand) (SEQ ID NO: 29)and 5'CCCAAGCTTGTACTCCAATG-3' (anti sense strand) (SEQ ID NO: 30). Theamino-terminal sense strand primer is homologous to pT7AD23K5 [Anderson,C. W., Virology, 177;259 (1990)] between the SalI site (G|TCGAC) and theNdeI site; following the NdeI recognition sequence are nine nucleotideshomologous to the Ad12 EP sequence. The carboxy-terminal anti-senseprimer has sequence corresponding the HindIII site (A|AGCTT; underlined)following the Ad12 EP termination codon. The amplified Ad12 EP gene wascleaved with SalI and HindIII and ligated with similarly cleavedpT7AD23K5 DNA. pT7AD23K16 was produced by cleaving pT7AD23K15 DNA withNdeI and religating. This removed the small NdeI fragment that encodesthe OmpT leader sequence [Anderson, C. W., Virology, 77;259 (1990)] andplaced the initiation codon for the Ad12 EP at the translation startsite of the pET-3 expression cassette.

Plasmid pT7AD23K18 (5225 bp) is a derivative of pT7AD23K8 that expressesthe EP sequence from the temperature-sensitive mutant, H2ts1 [Weber, J.,J. Virol., 17;462 (1976)]. The H2ts1 mutation lies between the BglIIsite at Ad2 nucleotide 21,816 and the KpnI site at 22,237 [Yeh-Kai, L.et al., J. Mol. Biol. 167;217 (1983)] [Roberts, R. J. et al., AdenovirusDNA: The Viral Genome and Its Expression (W. Doerfler, Ed.) 1-51(1986)]. This 422-bp fragment was isolated from restrictionenzyme-digested H2ts1 DNA by gel electrophoresis, and it was insertedinto pT7AD23K8 in place of the corresponding wild-type fragment. Thepresence of the H2ts1 mutation was confirmed by cleaving pT7AD23K8 andpT7AD23K18 with HaeIII; the tsl mutation removes a HaeIII restrictionsite present in the wild-type Ad2 sequence.

Expression of Recombinant Adenovirus Proteinases In Bacterial Cells

To obtain bacterial cells which express the recombinant adenovirusproteinases, the expression plasmids described above were used totransform an E. coli strain, BL21(DE3), which is capable of expressingthe T7 RNA polymerase. In BL21(DE3), the T7 RNA polymerase codingsequence is integrated into the bacterial chromosome 3' of theregulatory elements of the lactose operon. Thus, expression of the T7RNA polymerase can be induced by adding isopropylthiogalactoside (IPTG).T7 RNA polymerase efficiently transcribes a coding sequence insertedinto the expression cassette of a pET vector-based plasmid beginning atthe T7 φ10 promoter (see FIG. 1). Consequently, after IPTG induction,mRNA transcripts of the coding sequence accumulate rapidly, and theprotein product is synthesized at a high rate. Thus, in the pETvector/BL21(DE3) host cell expression system, IPTG induces expression ofthe recombinant adenovirus proteinase.

BL21(DE3) cells were transformed with each of the above-describedadenovirus proteinase expression plasmids. Transformed cells wereselected by ampicillin-resistance. Cultures of the transformed cellswere grown to mid-log phase, and IPTG was added to induce synthesis ofthe recombinant proteinase. Soluble extracts of the cells were thenprepared for characterization of the expression products.

The following terms will be used in describing the expression andcharacterization of recombinant adenovirus proteinases. A strain oftransformed cells is designated by the plasmid name/host bacterialstrain name, e.g., pT7AD23K5/BL21(DE3). The recombinant proteinaseproduced by expression of the plasmid is designated by the last four orfive characters (i.e., to accommodate 23K10) in the plasmid's name,e.g., 23K5. Precursor and processed forms of OmpT-proteinase fusionproteins, which can be detected as two separate bands onSDS-polyacrylamide gels, may be designated separately, e.g., 23K5a and23K5b.

FIG. 3 shows the expression of plasmids pT7AD23K5 and pT7 AD23K6 inBL21(DE3) cells after induction. Log phase cultures of untransformed(lanes c and f), pT7AD23K5-transformed (lanes d, g, and h), andpT7AD23K6-transformed (lanes e, i, and j) BL21(DE3) cells werepulse-labeled for 5 minutes with [³⁵ S]methionine at 1 (lanes g and i)and 2 hours (lanes c-f, h and j) after IPTG induction. Bacterialextracts were prepared immediately after labeling and run onSDS-polyacrylamide gels (SDS-PAG). Shown are a Coomassie Blue-stainedgel (left) and an autoradiogram of the gel (right). The positions of theproteinases, including precursor and processed fusion proteins, areindicated (arrows). The well-induced polypeptide just above these (lanesg-j) is probably β-lactamase. Proteins of purified Ad2 (lane a) andH2ts1 mutant virions (lane b) were also run on the gel.

As shown in FIG. 3, the recombinant proteinases quickly became the mostrapidly synthesized protein after induction, and rapid synthesiscontinued for more than 2 hours after induction (lanes f-j). Synthesisof the active 23K6 proteinase did not decrease over this prolongedperiod.

Nearly equal amounts of a 25 kDa protein (23K5a) and a 23 kDa protein(23K5b) were produced from pT7AD23K5 (lane d), suggesting that 23K5a and23K5b are the precursor and cleaved forms of the encoded OmpT-proteinasefusion protein. Pulse-chase experiments confirmed that a portion of the25 kDa protein was rapidly processed to the 23 kDa protein. The 25 kDaprotein that was not processed within about 5 minutes of synthesis wasstable, even several hours after synthesis. Amino-terminal sequenceanalysis indicated that the 23 kDa protein begins with serine₂₁ (seeFIG. 2; SEQ ID NO: 10). Similar results were obtained from expression ofpT7AD23K2 (Table 1). These results indicate that processing of the OmpTsignal peptide sequence of the fusion proteinases occurred as would beexpected if the OmpT leader were processed by the E. colimembrane-associated signal peptidase.

The 23K5 and 23K6 products were tested for solubility as an indicationof protein folding. Induced bacteria were harvested and lysed withlysozyme-EDTA, and 10,000×g supernatants were prepared. In each case,the majority of the proteinase was found in the insoluble pellet. Whenpellet fractions were analyzed by SDS-polyacrylamide gel electrophoresis(SDS-PAGE) in the absence of a reducing agent, only a small fraction ofthe proteinase protein entered the stacking gel, indicating that most ofthe bacterially synthesized proteinase was misfolded and crosslinkedthrough disulfide bonds. This was observed for both 23K5 precursor andprocessed proteins, as well as for the 23K6 proteinase.

Expression of the Mutant Proteinase Found in H2ts1 Ad2 Virus

Plasmid pT7AD23K18 expresses the mutant EP found in H2ts1 virus[Yeh-Kai, L. et al., J. Mol. Biol. 167;217 (1983)]. This plasmid wasmade by replacing the BglII-KpnI fragment in the EP gene of pT7AD23K8with the equivalent fragment from H2ts1 DNA. The recombinant H2ts1 EPwas expressed as well as the wild-type EP polypeptide, but it boundpoorly to the Zn-affinity column. A Sepharose column was substituted forthe Zn-affinity column purification step. No EP activity was observedwhen DEAE flow-through fractions from pT7AD23K18/BL21(DE3) were assayedin the presence of H2ts1 virions even though the H2ts1 proteinase hadbeen synthesized in cultures grown at 30° C., a temperature below thatrequired to obtain activity from H2ts1 virions. E. coli cytosol appearsto be a marginal environment for folding of the wild-type adenovirus EP;the H2ts1 EP may be sufficiently destabilized that it is unable to foldcorrectly in this foreign environment.

Activity and Amino-Terminal Sequences of the Recombinant Proteinases

The expression products of the above-described Ad2 and Ad12 proteinaseplasmids were tested for their ability to cleave the Ad2 major coreprotein precursor, pVII, in crude extracts from adenovirus-infectedcells. The extracts were obtained from human cells infected with thetemperature-sensitive mutant Ad2 strain, H2ts1, which has a defectiveproteinase. As described below, adenovirus proteinase activity requiresthe presence of two cofactors. Since these two cofactors are provided bythe crude extract in the assay, the proteinase activity determined bythis assay indicates that the adenovirus proteinase is functional, oractivatable. The recombinant proteinases were also characterized bypeptide sequence analysis of their aminotermini. Table 2 summarizes theresults of the activity assays and amino-terminal sequence analysis.

FIG. 4 shows the results of activity assays on 23K6 and 23K5. Bacterialextracts were incubated with the radiolabeled substrate (pVII). Sampleswere removed at different times and analyzed by SDS-PAGE andautoradiography. FIG. 4 shows an autoradiogram of samples taken after 90minutes of incubation. Appearance of the processed VII band andconcurrent decrease of the precursor pVII band indicates proteinaseactivity. Radiolabeled proteins of Ad2 virions were run on the gel toindicate the positions of pVII, VII, and other virion components (lanea). Extracts from Ad2-infected HeLa cells were assayed as a positivecontrol for proteinase activity (lane b). Lane e shows the results of anegative control, in which extracts from nontransformed BL21(DE3) cellswere assayed.

As shown in FIG. 4, the 23K6 proteinase possesses significant proteinaseactivity (lane d) in this assay system. Comparison of the assay atvarious time points indicated that the 23K6 proteinase caused rapidprocessing of the precursor pVII to VII. By 2 hours virtually all ofpVII had been converted to VII. 23K6 proteinase activity was distributedequally between soluble and insoluble fractions of the E. coli extract,despite the fact that the majority of the 23K6 was in the insolublefraction.

The recombinant Ad2 proteinases 23K6, 23K8, 23K10, and 23K13 and therecombinant Ad12 proteinase 23K16 were all found to be active in theassay. 23K6, 23K8, and 23K10 were further characterized by aminoterminalsequence analysis and found to have a mixture of aminotermini with andwithout the initiating methionine (Table 2). During synthesis of thesepolypeptides, the amino-terminal methionine of the nascent productappears to be occasionally removed by enzymes that are present in E.coli. The 23K6, 23K8, and 23K10 proteinases are thus expected to be amixture of 204 and 203 amino acid polypeptides. The relative amounts ofthe amino-termini with and without Met₁ for each of these proteinasesdiffered from experiment to experiment and could be as much as 50%.Deletion of the initiating methionine did not seem to be detrimental tothe function of the recombinant proteinase produced.

23K13, an Ad2 proteinase variant, was found to be as active as 23K6 inthe assay. Thus, the addition of a peptide sequence (SEQ ID NO: 4) tothe carboxy terminus of the proteinase did not appear to be detrimentalto proteinase function. 23K11, the Ad2 proteinase deletion variant,which lacks the nine amino acids from Glu₅ to Lys₁₃ (see SEQ ID NO: 2)near the aminoterminus, was not active in cleaving pVII, suggesting thatthe amino-terminal region is critical for the function of theproteinase.

In FIG. 4, the absence of the VII band in lane c indicates that the 23K5precursor and processed fusion proteins had no detectable activity. Noactivity was observed even after a 20 hour incubation. This finding issignificant in the context of production of foreign proteins in E. coli.Many foreign proteins fold improperly or inefficiently when expressed inE. coli. pT7AD23K5 was constructed with the hope that the proteinasepolypeptide might be transported by the OmpT signal sequence through theplasma membrane to the periplasm, where, after cleavage of the signalsequence, the polypeptide might fold into soluble, active proteinase.The processing of the 23K5 fusion protein in bacterial cells indicatedthat, although signal sequence cleavage occurred, proper folding and/ordisulfide bond formation did not.

Although no detectable activity was produced in pT7AD23K5-transfectedcells when grown to log phase and induced with IPTG, some proteinaseactivity was observed in extracts from uninduced cells grown tostationary phase. This activity was less than the activity of 23K6produced in induced, log phase cells. The other fusion proteinases, 23K1and 23K2, gave similar results. No proteinase activity was observed forthe deletion mutant protein, 23K11, when produced in either uninduced,stationary or induced, log phase cells.

Sequence Confirmation of the 23K6 Proteinase

Two amino-terminal sequences were identified for 23K6, which wereidentical except for the initial methionine (Table 2). The relativeamounts of the two aminotermini varied from experiment to experiment.Assuming that the structure of the proteinase coding sequence inpT7AD23K6 is correct and that no processing occurred at thecarboxyterminus, these amino-terminal sequences predict a 203 amino acidproteinase without the initiating methionine and a 204 amino acidproteinase with the methionine. Further sequence analysis was performedon tryptic peptides derived from 23K6. Together with the amino-terminalsequence, tryptic peptide analysis directly confirmed one-third of thepredicted proteinase sequence, including 24 residues of thecarboxy-terminal sequence (FIG. 6). Radiochemical sequence analysis ofthe insoluble fraction after trypsin digestion was also consistent withthe presence of Cys₁₇ and/or Cys₆₇, and Cys₁₂₂, Cys₁₂₆, and Cys₁₂₇.Thus, peptide sequence analysis confirmed that the 23K6 protein is the204 (or 203 without the initial methionine) amino acid Ad2 proteinasepredicted from the nucleotide sequence of the Ad2 genome (SEQ ID NO: 1and NO: 2).

Purification of Activatable Recombinant Adenovirus Proteinase from E.coli

A preferred scheme for purifying activatable recombinant proteinasesfrom E. coli is described in Example 9. Briefly, a culture oftransformed bacterial cells was grown to mid-log phase, and IPTG wasadded to induce synthesis of the recombinant proteinase. The lysedbacteria were centrifuged to separate the soluble (supernatant) and theinsoluble (pellet) fractions. Recombinant proteinase was purified fromthe soluble or supernatant fraction of lysed bacteria by DEAE-Sepharosechromatography, followed by affinity chromatography on zinc-loadedChelating-Sepharose. Greater than 90% of the protein in the eluate fromthe Chelating-Sepharose column is adenovirus proteinase as judged bySDS-PAGE. If required, the proteinase can be further purified on othersupports such as gel filtration and cation exchange columns. Recombinantproteinase, such as 23K6, purified by this method is highly active inthe crude extract assay.

Approximately 1-2 mg of purified, activatable Ad2 proteinase can beobtained from a liter of pT7AD23K6transformed cells (Example 9). Thehigh yield of functional 23K6 proteinase was found to be obtained if thetransformed cells were incubated at 30° C. rather than 37° C. afterinduction. Incubation at 37° produces a preparation in which most of thepolypeptides are misfolded; however, if the incubation temperature islowered to 30° at addition of IPTG, approximately half of therecombinant proteinase folds into a soluble protein and a higher yieldof activatable proteinase is obtained.

The substantial activity observed for the recombinant proteinase, 23K6,in the crude extract assay is significant in the context of bacterialproduction of foreign proteins. Expression of high amounts of a foreignprotein in bacterial host cells was expected to be detrimental to thegrowth of the bacterial cells or to solubility and correct folding ofthe protein in the cells, leading to poor yields of recombinantproteinase. However, prolonged synthesis of the 23K6 polypeptide ininduced cells (FIG. 3) and substantial yields of activatable 23K6 andother recombinant proteinases mentioned above indicated that these werenot critical problems in the method of production described herein. Asdiscussed, lowering the incubation temperature of the host cells afterinduction of proteinase expression to about 30° C. improves the yield ofactivatable protein. This is probably due to a slowing down of the rateof accumulation of the protein in the cell, which may favor functionalfolding of a higher proportion of the proteins expressed. This advantageis offset by the lower rate of total protein synthesis. Longerincubation times at lower temperatures than about 30° (e.g., 20°) mayresult in even better activity yields, if the recombinant proteins arestable in the cell. Optimization of the incubation temperature andtesting of other growth conditions to improve yield, especially growthconditions which slow the rate of protein synthesis in the host cells,can be performed using the methods of production and proteinase assaysdescribed herein.

Production of Activatable Recombinant Proteinase in a BaculovirusVector/Insect Cell Expression System

A baculovirus vector, vNPVAd2EP, was made for expressing the Ad2proteinase in Sf9 insect cells (Example 10). In the vector, the Ad2proteinase coding sequence replaces the polyhedron protein gene. Therecombinant Ad2 proteinase was purified by a procedure similar to thatdescribed above for purification from E. coli, and found to be active inthe crude extract assay.

Adenovirus Proteinase Activity Requires Two Cofactors

Two assays were developed to monitor proteinase activity in the absenceof adenovirus virions or infected cell extracts. The first involved useof recombinant proteins containing a leader sequence connected to aprotein through an amino acid segment corresponding to an adenovirusproteinase recognition and cleavage sequence. The second involvedsynthesis of a fluorogenic compound, a peptide derivative of rhodaminewhich, when cleaved by the adenovirus proteinase, becomes highlyfluorescent.

Recombinant protein substrates that resemble natural virion precursors,such as pVI, can be produced in E. coli by genetic engineering methodssimilar to those used for expression of recombinant adenovirusproteinase. The recombinant substrate may have an artificial leadersequence that can be removed by proteinase-mediated cleavage. The leadercan be designed to aid in purification of the substrate; thus therecombinant substrate can be produced and purified much more efficientlythan natural adenovirus substrates. Recombinant protein substrates alsoserve as prototypes of potential commercial products, showing that theadenovirus proteinase will remove an artificial leader sequence from arecombinant protein that is not related to any adenovirus protein. Thefirst artificial protein substrate was called HEP1DBP. It consists of a17 amino acid leader(Met-Ala-Ser-Met-Thr-Gly-His-His-His-His-His-His-Gly-Met-Ser-Gly-Gly-)(SEQ ID NO: 37) attached to the initiating methionine of the 232 aminoacid DNA binding protein (DBP), of bacteriophage T7. The T7 DBP is theproduct of gene 2.5. The recombinant proteinase substrate is produced byinduction of a pET expression plasmid called pT7HEP1DBP (also calledpT7HIS2) (FIG. 7A and Example 11); the predicted sequence of theexpressed substrate is given in Table 1. The leader sequence containssix consecutive histidine residues to permit purification by metalaffinity chromatography in a manner analogous to purification of theadenovirus proteinase. Immediately preceding the methioninecorresponding to the initiation site of the T7 DBP is the tetra-aminopeptide element -Met-Ser-Gly-Gly- (SEQ ID NO: 38). This segmentcorresponds to the proteinase recognition sequence in the adenovirusvirion precursor polypeptide pVI. The size of the leader sequence waschosen so that the substrate precursor HEP1DBP, and the predicted majorproduct after cleavage, the T7 DBP, could easily be distinguished bySDS-polyacrylamide gel electrophoresis.

                                      TABLE 1                                     __________________________________________________________________________    Predicted Sequence and Composition of the                                     Expression Product Recombinant Adenovirus                                     Proteinase Substrate pT7HEP1DBP                                               __________________________________________________________________________    Segment: 4092-4841                                                            Composition 249 Residues                                                      22 Ala A    3 Cys C                                                                               8 His H                                                                               8 Met M                                                                              11 Thr T                                    6 Arg R    3 Gln Q                                                                               7 Ile I                                                                               9 Phe F                                                                               3 Trp W                                    8 Asn N   26 Glu E                                                                              10 Leu L                                                                              13 Pro P                                                                              11 Tyr Y                                   20 Asp D   24 Gly G                                                                              25 Lys K                                                                              14 Ser S                                                                              18 Val V                                              5         10        15        20                                    1 M A S M T G H H H H H H G M S G G M    A                                                                        K                                         21                                                                              K I F T S A L G T A E P Y A Y I A K    P                                                                        D                                         41                                                                              Y G N E E R G F G N P R G V Y K V D    L                                                                        T                                         61                                                                              I P N K D P R C Q R M V D E I V K C    H                                                                        E                                         81                                                                              E A Y A A A V E E Y E A N P P A V A    R                                                                        G                                        101                                                                              K K P L K P Y E G D M P F F D N G D    G                                                                        T                                        121                                                                              T T F K F K C Y A S F Q D K K T K E    T                                                                        K                                        141                                                                              H I N L V V V D S K G K K M E D V P    I                                                                        I                                        161                                                                              G G G S K L K V K Y S L V P Y K W N    T                                                                        A                                        181                                                                              V G A S V K L Q L E S V M L V E L A    T                                                                        F                                        201                                                                              G G G E D D W A D E V E E N G Y V A    S                                                                        G                                        221                                                                              S A K A S K P R D E E S W D E D D E    E                                                                        S                                        241                                                                              E E A D E D G D F *                                                        __________________________________________________________________________     NB: Ad2 proteinase cleaves after residue 17; residues 14-17 correspond to     the sequence of Ad2 virion component pVI immediately before the               aminoterminal cleavage site; T7 Gene product 2.5 sequence starts at           residue 18.                                                              

When purified HEP1DBP was incubated with disrupted wild-type adenovirus2 virions, it was cleaved, as determined from the change in its mobilityduring SDS-polyacrylamide gel electrophoresis. No cleavage was observedwhen incubation was with disrupted H2ts1 virions alone. Surprisingly, nocleavage was observed when HEP1DBP was incubated with purified 23K6 or23K8 alone, but cleavage was obtained when purified 23K8, HEP1DBP, anddisrupted H2ts1 virions were incubated together. Furthermore, proteinsequence analysis showed that cleavage occurred between the last aminoacid of the leader sequence and the methionine corresponding to thestart of T7 DBP, as expected for Ad2 proteinase activity. These resultsshowed that one or more additional components are required foractivation of the Ad2 proteinase and that these cofactors are present inadenovirus virions. The addition of purified adenovirus DNA to reactionscontaining 23K8 and HEP1DBP did not stimulate cleavage of the HEP1DBPsubstrate. This result suggested that one proteinase cofactor was aprotein or peptide. That one cofactor was protein was confirmed by thefinding that preincubation of H2ts1 virions with trypsin, and subsequentinactivation of the trypsin (by adding a trypsin inhibitor, soybeantrypsin inhibitor, that does not inhibit the adenovirus proteinase)inactivated a component in H2ts1 virions required for proteinaseactivity.

The nature of the proteinase cofactor(s) was pursued with the aid of thesecond assay, which utilizes the substrate (Leu-Arg-Gly-Gly-NH)₂-rhodamine. The design of this substrate was based on two facts. (1) Itwas known that the proteinase present in disrupted Ad2 virions wouldcleave small peptides with sequence similar to that found at naturalcleavage sites in adenovirus virion precursors. (2) Cleavage of eithertetra-peptide sequence from the substituted rhodamine substrate producesa very large increase, up to a 3500-fold, in fluorescence. Underconditions where only a small fraction of the rhodamine substrate iscleaved, the increase in fluorescence is proportional to the amount ofproteinase present and to the time of incubation. Thus, the fluorescenceassay provides a quantitative method for assessing proteinase activitythat is more sensitive convenient and rapid than the gel electrophoresisassay.

FIG. 7B shows the initial results of the fluorescence assay. Disruptedwild type Ad2 virus was positive and disrupted H2ts1 virus was negativefor activity, as expected. However, purified recombinant Ad2 proteinasegave no activity. Activity was obtained from the recombinant proteinasecomplemented with disrupted H2ts1 virus. This suggested that cofactorspresent in adenovirus are required for activation of the proteinase. Asdescribed herein, it has been determined that activation of the purifiedrecombinant proteinase (referred to as rEP or an activatable proteinase)required the presence of two cofactors.

One cofactor was found to be DNA. When disrupted H2ts1 virus was treatedwith DNase prior to the assay, 94% of the proteinase activity obtainedwith untreated H2ts1 virus was lost (FIG. 8). Subsequent addition of Ad2viral DNA restored activity to about 70% of that obtained with untreatedH2ts1 virus (A and C). To determine whether proteinase activity wasdependent on specific nucleotide sequences, various polymers were latersubstituted for Ad2 DNA (Table 3). No sequence-specific requirement wasevident. Not only did T7 DNA substitute for Ad2 DNA, but alsosingle-stranded DNAs, circular single- and double-stranded DNAs, andeven transfer RNA. Rather, it appeared as if the requirement was for apolymer with high negative charge density. Polyglutamic acid,polyaspartic acid and heparin substituted for Ad2 DNA in vitro but notthe four deoxyribonucleoside monophosphates, glutamic acid, asparticacid or polylysine (Table 3).

The use of DNA as a cofactor of adenovirus proteinase activity is novelfor a proteinase, and suggests the existence of a new class ofDNA-dependent proteinases. The viral DNA is most probably required forproteinase activity in Ad2 virions, because proteinase activity withdisrupted ts-1 virions is lost on treatment with DNase and is restoredon addition of Ad2 DNA.

Adenoviral DNA along with the recombinant proteinase was insufficient toreconstitute proteinase activity (FIG. 8D), suggesting the requirementfor another cofactor. As described above, results indicated that thesecond cofactor is a protein (FIG. 9).

The protein cofactor was purified by filtration through a membrane witha 30 kda molecular weight cutoff pore size, followed by reverse phasechromatography (FIGS. 10 and 11; Example 12). Three peaks from thereverse phase column contained proteinase activity (FIG. 11). Of thetotal cofactor activity applied to the column, 7% was recovered in peaka, 22% in peak b, and 14% in peak c. The final yield was greater than49%.

The amino acid sequence of the proteins in each of the three peaks wasdetermined. The results indicate that the proteins in the three peakshave almost identical amino acid sequences (FIG. 12; amino acids 240-250of SEQ ID NO: 15). The differences were in the yield of lysine atposition 6, suggesting a modified lysine residue at this position. Noamino acid was detected at position 10 where a cysteine is expected. The11 amino acid sequence corresponds to the carboxy terminus of theprecursor to the Ad2 virion component VI (pVI, whose predicted aminoacid sequence is also shown in FIG. 12; SEQ ID NO: 15). The pVI sequencehas two consensus cleavage sequences, one beginning at residue 29, MSGG,and the other at 236, IVGL (underlined). Cleavage at the latter sitewould liberate the 11 amino acid cofactor.

The requirement for the 11-amino acid second cofactor from the carboxyterminus of pVI seemed to be specific. A peptide similar in character,Cys-Gly-Tyr-Gly-Pro-Lys-Lys-Lys-Arg-Lys-Val-Gly-Gly, did not substitutefor the pVI-c peptide.

The viral DNA and pVI-c peptide may be required for proteinase activityin vivo to ensure that virion precursor proteins are processed onlyafter virion assembly; otherwise, they may not be able to assemble intoa virus particle. Perhaps the viral DNA serves as a scaffold for theassembly of proteinase complexes adjacent to the >3,000 processing sitesthat must be cleaved to produce an infectious virus particle.Alternatively, the viral DNA could serve as a guide wire on which theproteinase complex moves as it cleaves precursor proteins.

After determining the identity of the two cofactors, reconstitution ofadenovirus proteinase activity in vitro with purified components wasaccomplished. FIG. 13 shows titration with (a) pVI-c peptide and (b) Ad2DNA. In (a), Assays in 1 ml contained 1.2 nM rEP protein, 11.9 pM Ad2DNA and the indicated concentrations of pVI-c peptide. The rate ofsubstrate hydrolysis is the rate in the reaction minus the rate with therEP protein and Ad2 DNA alone which was 0.068 pmol min⁻¹. In (b), Assaysin 1 ml contained 1.2 nM rEP protein, 36 nM pVI-c peptide and theindicated concentrations of Ad2 DNA. The rate of substrate hydrolysis isthe rate in the reaction minus the rate with the rEP protein and pVI-calone which was 2.76 pmol min⁻¹. The concentration of(Leu-Arg-Gly-Gly-NH)₂ -rhodamine was 5 μM, and its rate of hydrolysis toLeu-Arg-Gly-Gly-NH-rhodamine was determined by measuring the increase influorescence every 3 minutes for 15 minutes. The pVI-c peptide wasassembled in a peptide synthesizer.

The Carboxy-Terminal Fragment of Ad12 pVI is Also a Proteinase Co-factor

After the 11-amino acid pVI-c fragment was shown to be a cofactor forAd2 proteinase, the equivalent fragment from Ad12 was tested forcofactor activity. The equivalent Ad12 fragment differs from thecorresponding Ad2 fragment at only two amino acids.

The proteinase activity in disrupted, wild-type Ad12 virions will cleavethe HEP1DBP substrate, but the Ad12 virion EP activity is poor comparedto the activity from an equivalent number of Ad2 virions. Cleavage ofthe [³⁵ S]-methionine-labeled HEP1DBP substrate was greatly enhanced,however, by the presence of purified Ad2 rEP (Example 21). This resultshowed that Ad12 virions also contain components that complement andactivate the Ad2 EP polypeptide.

To determine if the Ad12 carboxy-terminal fragment of pVI functioned asthe EP co-factor, the corresponding synthetic peptide was mixed withrecombinant Ad2 proteinase and Ad2 DNA, and incubated with the HEP1DBPsubstrate. Rapid and complete cleavage of the HEP1DBP substrate wasobtained when the incubations contained either Ad12 or Ad2 synthetic pVIcarboxy-terminal peptide, but no cleavage was observed in incubationswith a control peptide of similar length and composition.

Sequence of the Ad12 Genes for pMu and pVI

Ad2 and Ad12 virions have similar polypeptide compositions but severalcomponents differ significantly in apparent molecular weight. Virionprecursors pMu and pVI are encoded by adjacent genes in the L3 region ofadenovirus genomes, between the genes for the minor core protein (V) andhexon (II). Each of these Ad2 components is cleaved at two EP consensussites, one near the amino termini, the other near the carboxy termini.Ad2 Mu is a 19 amino acid peptide that binds strongly to DNA; componentVI is associated with hexons.

By analogy with the Ad2 genome (Genbank codename ADRCG), the Ad12 genesfor pMu and pVI were predicted to lie within the adjacent BamHIendounclease cleavage fragments I, J, and F. These fragments were clonedinto the BamHI site of pBR322 and sequenced, using a primer-directedstrategy as in Example 8. The Ad12 BamHI J fragment is 236 bp long andwas sequenced entirely using vector-specific sequencing primers. Bothends of the BamHI I and F fragments were sequenced. Sequence from oneend of the F fragment was homologous to Ad2 sequence near the carboxyterminus of pVI and extended toward the hexon gene. A reverse primer,corresponding to sequence near the amino terminus of the hexon gene, wasused to obtain the complementary sequence. Sequence from one end of theI fragment was complementary to the late (sense) strand of Ad2, and thissequence was extended to the carboxy terminus of the gene for componentV with appropriate primers; the complementary sequence was determined inthe same manner. The portion of the sequence determined on both strandsis given in SEQ ID NO: 39, together with the deduced amino acidsequences of pMu and pVI. Consensus EP cleavage sites are present inboth sequences at positions equivalent to the cleavage sites in the Ad2percursors.

The Ad12 precursor for Mu has only 72 residues compared to 80 residuesfor Ad2 pMu; Ad12 Mu has only 15 residues. Ad12 and Ad2 pMu areidentical at 45 of 72 amino acid positions (62.5% identity). The maindifference in length results from a 15 base pair deletion immediatelybefore the amino-terminal EP cleavage site and a 12 bp deletion afterthe cleavage site. It is remarkable, therefore, that an amino-terminalEP cleavage site has been retained; however, this cleavage site has notbeen completely conserved. Ad2 pMu has a type I cleavage site(-LTGG-|-M-) at this position with glycine at both the P1 and P2positions, Ad12 pMu has a type II site (-LTGN-|-G-), which has glycinesat the P2 and P1' positions. Although changes at the nucleotide levelare evident at each of the other three cleavage sites (thecarboxy-terminal pMu site and both pVI sites), these sites are morehighly conserved.

The carboxy-terminal fragments of the two pMu sequences are highlyconserved with identity at 24 of 29 positions (83%). This observationsuggests that the carboxy-terminal fragment may be a functional domainthat, for example, associates with another virion component. Bothcentral Mu domains are highly basic and are expected to bind strongly toDNA. Thus, pMu may cement the core to the shell or help to condense thecore. EP cleavage after assembly would disrupt such associations.

The Ad12 pVI sequence is predicted to be 265 residues in length, fifteenresidues longer than Ad2 pVI (Akusjarvi and Persson, 1981). Theamino-terminal cleavage fragment of Ad12 pVI is predicted to be 33residues, the same length as the Ad2 amino-terminal fragment. Thecarboxy-terminal fragment is 11 residues in length as is the Ad2fragment. The 15 residue difference in length falls entirely with thebody of VI and results primarily from four short insertions in the Ad12genome. Ad12 VI has a notably slower mobility than Ad2 VI duringSDS-polyacrylamide gel electrophoresis. As noted above, thecarboxy-terminal halves of Ad12 and Ad2 VI are the least conservedportions of pVI. The two cleavage fragments are highly conserved withmost differences due to conservative substitutions. These observationssuggest that the terminal domains of pVI also may have biologicalfunction.

The Ad12 EP polypeptide is very similar in sequence to the Ad2 EPpolypeptide sequence (Houde and Weber, 1988); thus, we expect that theAd12 EP has similar requirements for cofactors. Although we have nottested this hypothesis directly, the high homology between thecarboxy-terminal fragments of Ad12 and Ad2 pVI suggested that the Ad12fragment might substitute for its Ad2 counterpart; this was found to bethe case. Both peptides are very basic (˜50% Arg plus Lys), and like Mu,should interact strongly with a polyanion, such as DNA. Because of aglutamine-to-lysine substitution at the second position, the Ad12fragment has one more positively charged residue than the Ad2 fragment.The other amino acid difference is at the carboxy-terminal residue; theAd12 fragment has a tyrosine in place of the phenylalanine of Ad2. Bothfragments have a cysteine at the tenth position, and the effect ofderivitizing this residue suggests that it may be important forco-factor activity.

Identification of Ad12 Cleavage Sites

To determine if the postulated Ad12 pMu and pVI cleavage sites werefunctional, CsCl-purified Ad12 virions were fractionated as in Example20, and individual components were subjected to amino acid sequenceanalysis. Because the cleavage products of Mu and the carboxy-terminalfragment of pVI were expected to be small peptides, virion componentswere fractionated first by size, using a filter with a molecular weightcut-off of 10,000 Da. After collecting the filtrate from virionsdisrupted in 10 percent pyridine, the retentate was treated with 1Mammonium bicarbonate to release DNA-bound peptides, and this wash wasagain subjected to filtration. Peptides in each filtrate wereconcentrated and then fractionated separately by reverse phase HPLC.Each peptide peak was then subjected to automated Edman degradation. Forseveral components, no sequence was detected. This result was expectedbecause the precursors to adenovirus structural proteins are thought tobe acetylated. Clear sequence was obtained, however, for six components.These sequences were homologous to expected cleavage fragments from theAd2 precursors pIIIa, pVIII, pMu, and pVI. One component corresponded tothe predicted fifteen amino acid sequence of Ad12 Mu, anothercorresponded to the amino terminus of the predicted carboxy-terminalfragment of pMu, and a third to the predicted eleven amino acidcarboxy-terminal fragment of pVI. Thus, pMu clearly must be cleaved atthe two sites predicted from the Ad2 EP consensus recognition sequence,and pVI is cleaved at the predicted carboxy-terminal site. For the otherthree fragments that yielded sequence, two are provisionally identifiedby homology with the corresponding Ad2 sequence for pVIII, and the otherby homology with the carboxy-terminus of Ad2 pIIIa. The amino terminusof each fragment corresponds to the position of an EP cleavage site inthe corresponding Ad2 protein.

To determine if the amino-terminal pVI site was cleaved, CsCl-purifiedAd12 virions were fractionated by SDS-polyacrylamide gelelectrophoresis, and the separated polypeptides were transferredelectrophoretically to a PVDF (Immobilon) membrane. Portions of themembrane corresponding to the positions of VI and VII were excised andthen sequenced. The sequence from VI corresponded to the expectedsequence beginning at the predicted cleavage site (FIG. 2). The sequenceobtained from Ad12 VII was strikingly similar to the amino-terminalsequence of Ad2 VII. These results indicated that Ad12 pVI cleaved atsites homologous to the Ad2 pVI cleavage sites. The sequence of the Ad12pVII gene has not been determined and confirms the predicted cleavagesite.

Preparation and Characterization of an Anti-Ad2 Proteinase Antibody

A polyclonal antiserum was prepared by immunizing rabbits with purified23K1 polypeptide. 23K1 is a fusion protein composed of the T7 gene 10protein joined to the Ad2 proteinase (Table 2). The antiserum,designated α23K1, was strongly immunoreactive with Ad2 proteinase andnot significantly reactive with other adenovirus or mammalian cellproteins (FIGS. 14 and 15). The α23K1 antiserum reacted with Ad2proteinases in purified virions, virus-infected HeLa cells, andbacterial extracts. It was immunoreactive with wild type Ad2, mutantH2ts1, recombinant fusion (23K5) and recombinant variant (23K11)proteinases. This antibody recognized active (23K6 and 23K10) andinactive (23K11) proteinases. Thus, the α23K1 antibody was characterizedas immunospecific for Ad2 proteinase.

Uses of the Invention

This invention provides a method for producing activatable recombinantadenovirus proteinases in nonmammalian and mammalian host cells. Themethod comprises: a) obtaining an expression construct comprising anadenovirus proteinase coding sequence inserted in a vector suitable forexpressing heterologous proteins in a suitable host cell; b) introducingthe expression construct into the host cell, thereby, obtaining a hostcell containing the expression construct; and c) growing the host cellcontaining the expression construct under conditions suitable forexpressing the adenovirus proteinase coding sequence, thereby, producinghost cells which express the recombinant adenovirus proteinase.

This invention further provides expression constructs for producingactivatable recombinant adenovirus proteinases in host cells. Theexpression constructs comprise an adenovirus proteinase coding sequenceinserted in a vector suitable for expression of heterologous proteins inthe host cell used. Besides bacterial expression vector/host cellsystems (such as described above), other expression systems, such asyeast or insect, as well as mammalian expression systems, may be used.The expression constructs are introduced into the host cells by knownmethods (e.g., transformation, transfection, or infection). Theadenovirus proteinase coding sequence may exist as an episome or beintegrated into the chromosome of the host cell. Several vector/hostcell systems for expressing foreign proteins and methods of introducingconstructs into cells have been described in the published literature orare commercially available.

Two proteinase expression constructs of this invention useful forproteinase production are the plasmid pT7AD23K6 and the plasmidpT7AD23K8, whose expression results in the production of activatablerecombinant Ad2 proteinase (23K6 and 23K8, respectively). Proteinasevariants with altered carboxy-terminal sequences, such as 23K13, canalso be synthesized to provide proteinases with additional potentiallyuseful properties. As described above, addition of up to nine aminoacids to the carboxyterminus of the Ad2 proteinase does not appear tohave a detrimental effect on activity. In contrast, variants of the Ad2proteinase which have amino acid additions or deletions in theamino-terminal region are less activatable or inactive. Thus, proteinaseexpression constructs with alterations of the aminoterminal region ofthe coding sequence may not be useful for production of functionalrecombinant proteinase. The above results show that deletions in theamino-terminal region as short as nine codons and additions to theamino-terminus as short as three codons can significantly reduce orabolish the yield of proteinase activity. Post-translational deletion ofthe initiating methionine does not appear to affect the yield ofactivity.

pT7AD23K6 can also serve as a prototype for the construction ofexpression constructs encoding other adenovirus type proteinases. Thework described herein demonstrates that activatable recombinantproteinase of an adenovirus (Ad12) from a different subclass can beproduced using a plasmid, pT7AD23K16, which follows the design of theprototype construct. A high degree of homology has been demonstratedamong the proteinase genes of various serotypes of adenovirus. This DNAsequence homology extends even to serotypes of different host ranges(see, e.g., Cai and Weber, Virology 196, 358 (1993) and referencestherein). Because of this homolgy, production of activatable proteinasesof other adenovirus types is expected using the expression constructsand methods taught by this invention. FIG. 16 shows the predicted aminoacid sequences of several adenovirus proteinases (Example 19; SEQ ID NO:2, NO: 6, and NOS: 16-21). Nucleotide sequences encoding theseproteinases can be inserted into known expression vectors, such as pETbacterial vectors.

Nucleic acid (DNA or RNA) encoding adenovirus proteinases can beobtained from a number of sources, including adenovirus stock, fromcloned adenoviral DNA, and by using polymerase chain reactiontechniques. Expression constructs can be obtained using recombinant DNAtechniques (see, e.g., Sambrook et al., Molecular Cloning: A LaboratoryManual, 2nd Edition, Cold Spring Harbor Laboratory Press; Ausubel et al.(eds.), Current Protocols in Molecular Biology, Greene PublishingAssociates and Wiley-Interscience, New York).

The activity of other recombinant adenovirus type proteinases can beassayed as described herein for the recombinant Ad2 proteinase. As shownabove, recombinant Ad12 proteinase is active in an assay using asubstrate (pVII) and cofactors derived from Ad2-infected cells.Furthermore, the cleavage site sequences of the Ad2 and Ad12 pVIprecursor proteins are conserved. In addition, heat inactivated Ad12virions complement the recombinant Ad2 proteinase (23K6 or 23K8) toproduce proteinase with even higher activity than is produced with anequivalent number of heat inactivated Ad2 virions. This result suggeststhat Ad12 co-factors work as well or better to produce an activatedenzyme with 23K8 than do the homologous cofactors in Ad2 virions. Thus,an optimal proteinase enzyme may be produced by combining co-factors andsequence elements from different adenovirus serotypes. These may becreated and expressed using standard genetic engineering techniques andthe teaching provided in this document. These results suggest that alladenovirus type proteinases have very similar or identical cleavagesites.

This invention provides the means to obtain quantities of activatableadenovirus proteinase not previously possible. The recombinantproteinase produced can be purified to near homogeneity as determined bySDS-polyacrylamide gel electrophoresis. The recombinant adenovirusproteinase produced is functional and can be used in studies on thestructure, biochemical properties, and function of the adenovirusproteinase. It can also be used to study virion assembly and maturationand virion protein processing in adenoviruses.

As reported herein, activation of the adenovirus proteinase requires twocofactors. The cofactors have been identified and, together withpurified recombinant proteinase, have been shown to reconstituteadenovirus proteinase activity in vitro using purified components. Thus,this invention provides preparations of activated adenovirus proteinaseand methods for producing the activated preparations.

A preparation of activated adenovirus proteinase consists essentially ofan activatable recombinant adenovirus proteinase, polyanion, and apeptide cofactor of adenovirus proteinase activity. The polyanioncofactor can be single-stranded or double-stranded DNA, RNA,polyglutamic acid, polyaspartic acid or heparin.

A peptide cofactor of adenovirus proteinase activity is a protein,generally a short peptide, which is able to activate an activatableadenovirus proteinase in combination with DNA. Peptide cofactors ofadenovirus proteinase activity can be identified by a method comprising:a) obtaining a peptide; b) combining the peptide with an activatablerecombinant adenovirus proteinase, DNA, and an appropriate substrate ofadenovirus proteinase, under conditions suitable for cleavage of thesubstrate by the recombinant adenovirus proteinase; and c) determiningcleavage of the substrate wherein cleavage of the substrate indicatesthat the peptide is a peptide cofactor of adenovirus proteinaseactivity.

An appropriate substrate of adenovirus proteinase is any moleculecontaining the peptide recognition sequence of an adenovirus proteinase.For example, the substrate protein may contain the Ad2 proteinaserecognition sequence. The Ad2 EP consensus recognition sequence wasdetermined to be --(L, I, M)-X-G-G|X-- or --(L, I, M)-X-G-X|G--, wherethe vertical line denotes the position of cleavage; the P3 (X) positionappears to be unimportant for cleavage [Anderson, C. W., Virology,177;259 (1990); Webster, et al., J. Gen. Virol., 70;3225 (1989)]. Asdescribed herein, both recombinant Ad2 and Ad12 proteinases cleavepeptides containing this sequence, and it is expected that proteinasesof other adenovirus types will also recognize this sequence. Afluorogenic substrate, (Leu-Arg-Gly-Gly-NH₂ -rhodamine has beendescribed. Other peptide-rhodamine substrates have been described in thepublications of Walter Mangel. Cleavage of the substrate can be detectedby changes in size, for instance, as seen by SDS-PAGE, in fluorescence,or some other property.

A peptide cofactor from Ad2 is described herein, which is 11 amino acidslong and has the carboxyterminal sequence, GVQSLKRRRCF, of the Ad2protein, pVI (SEQ ID NO: 15), in which the lysine may be modified. This11 amino acid peptide cofactor can be obtained in crude extracts fromadenovirus-, including H2ts1-, infected cells, or purified by themethods described in Example 12. The equivalent 11-amino acid carboxyterminal peptide from Ad12 pVI (see SEQ ID NO: 41) can substitute as thepeptide cofactor.

Activated adenovirus proteinase preparations can be used to cleave aselected protein at a specific site by a method comprising: a) obtaininga substrate protein comprising the selected protein and an adenovirusproteinase recognition sequence located at the desired cleavage site;and b) combining the substrate protein with an activated adenovirusproteinase preparation. The substrate protein can be constructed usingrecombinant DNA techniques. The cleavage of the target protein may occurin a purified system or in cellular extracts. The timing of the cleavageevent may be controlled by combining the substrate with the proteinaseand DNA cofactor, then, initiating the cleavage by adding the peptidecofactor. For example, an activated proteinase preparation used in thismethod may contain purified recombinant 23K6 proteinase, bacterial DNA,and purified peptide cofactor.

Specific cleavage of proteins can be used to purify proteins or portionsof proteins. For example, the method can be used to purify smallpeptides which are difficult to purify. A fusion protein can beengineered which contains the peptide linked to a reagent moiety with aproteinase cleavage site at the junction of peptide and binding moiety.After the fusion protein is purified using a property conferred on thefusion protein by the reagent moiety, such as specific binding to anaffinity column or increased size, the peptide can be purified from thereagent moiety by cleavage of the fusion protein with the activatedproteinase preparation.

In another example, a substrate protein can be genetically engineered tocontain the proteinase recognition sequence at a position in its primarystructure such that cleavage of the protein results in deletion of afunctional domain of the protein.

This invention also provides variant or mutant adenovirus proteinaseswith unusual, potentially useful properties, such as altered cleavingability. An activatable variant Ad2 proteinase, 23K13, has beendescribed herein. Studies of 23K13 and other proteinase variants (23K11,23K5) lead to the expectation that other variant proteinases withalterations of the carboxy-terminal region of the proteinase will befunctional, but variants with alterations of the amino-terminal region(except loss of the initiating methionine) will be inactive or much lessactive. For example, a specific deletion of amino-terminal sequencesproduces an inactive proteinase. It is likely that the deletion orchange of conserved residues (as indicated in FIG. 16) will produceinactive or less active proteinase, whereas changes to or insertions atnon-conserved sequences may do little harm and may permit engineering ofproteinase with enhanced or specialized properties. In addition, aproteinase which would be particularly useful in commercial applicationsis produced by the peptide having coupling the carboxy-terminal sequenceof pVI to the carboxy terminus of the recombinant proteinase. It is alsopossible to produce a mutant proteinase that does not require DNA foractivity.

Furthermore, this invention provides a method to identify novel variantadenovirus proteinases with altered proteinase activity. The methodcomprises: a) obtaining a recombinant variant adenovirus proteinase; b)combining the recombinant variant proteinase with an adenovirusproteinase substrate, DNA or other polyanion cofactor, and a peptidecofactor of adenovirus proteinase activity; and c) comparing theactivity of the recombinant variant proteinase with that of the wildtype proteinase, wherein a difference in activity indicates that theadenovirus proteinase variant has altered proteinase activity.

The primary structure of the proteinase variant can be determined beforeor after performing the identification. A mutation resulting in adefective proteinase can then be engineered into an adenovirus strain byrecombinant techniques, thus, producing adenovirus strains which aredefective in aspects of virion maturation. Such mutant adenovirusstrains may be useful as vaccine strains or to produce virions asdelivery vehicles for gene therapy. The temperature sensitive mutant Ad2strain, H2ts1, has been shown to produce immature virions atnonpermissive temperatures, which attach to cells but do notproductively infect them (Weber, 1976 supra; Hannan et al., 1983 supra;Mirza et al., 1980 supra).

The above-described method can be used to generate and screen noveladenovirus strains with mutant proteinases. For example, mutantproteinases can be generated by random mutagenesis of a construct suchas pT7AD23K6 and produced in E. coli. The recombinant proteinases canthen be assayed as described previously. Production and preliminaryscreening of variant adenovirus proteinases in vitro or in fast-growingmicrobial cell culture can reduce the time and cost of developingimproved adenovirus strains.

Analysis of structural variations (or mutations) resulting in alteredproteinase activity can also provide insights into adenovirus proteinasefunction, such as the interaction of the cofactors with the proteinase.

Alternatively, variants of the above-described 11 amino acid peptidecofactors can be generated and identified by a similar method. Variantpeptide cofactors with mutations or side-chain modifications of the 11amino acid peptide can be produced by recombinant techniques,synthesized, and chemically modified. The variant cofactors can then betested for effect on proteinase activity in assays as describedpreviously. Variations in size and sequence may result in functionallyequivalent peptide cofactors of proteinase activity, or they may resultin peptides with altered ability to activate adenovirus proteinases.Adenovirus strains with variant cofactors can be engineered by alteringthe coding sequence of the pVI protein.

Activated recombinant proteinase preparations can also be used toidentify substances which affect proteinase activity agonistically orantagonistically. A method for identifying a substance which is anagonist or antagonist of adenovirus proteinase activity comprises: a)obtaining an activated adenovirus proteinase preparation; b) combiningthe activated proteinase with the substance; and c) Comparing theproteinase activity obtained with the substance to proteinase activitywithout the substance, wherein a difference in activity indicates thatthe substance is an agonist or antagonist of adenovirus proteinaseactivity. Substances identified by this assay method may affectprimarily the recombinant proteinase or the peptide cofactor in thepreparation. Such substances are expected to affect adenovirus virionproduction in vivo, and thus, are potential pharmaceuticals for treatingadenovirus infections or modulating adenovirus vaccines.

This invention also provides a method for preparing antibodies which areimmunoreactive with an adenovirus proteinase. The method compriseseliciting an immune response against a recombinant adenovirusproteinase, or a portion of an adenovirus proteinase. Described hereinis a polyclonal antiserum, α23K1, which was prepared by immunizingrabbits with the 23K1 recombinant proteinase. 23K1 is a fusion proteincomposed of the T7 gene 10 protein fused to the Ad2 proteinase. α23K1antibody recognizes Ad2 wild type, mutant, and recombinant proteinasesbut is not significantly reactive with other adenovirus or mammaliancell proteins. Polyclonal and monoclonal antibody preparationsimmunospecific for a variety of adenovirus proteinases can be preparedby using recombinant proteinases, or portions thereof, as immunogens oras haptens. Techniques for preparing antibodies have been described(see, e.g., Harlow and Lane, Antibodies: A Laboratory Manual, ColdSpring Harbor Laboratory Press, 1988).

Immunospecific anti-proteinase antibodies prepared as described abovecan be used as immunoprobes for the adenovirus proteinase, for example,in Western blot analysis or in immunoassays. A method for detecting anadenovirus proteinase in a sample comprises: a) obtaining an antibodyprepared as described above, which is immunospecific for the adenovirusproteinase in distinction from other adenovirus or mammalian cellproteins; b) combining the antibody with the sample under conditionsappropriate for specific binding of the antibody to the adenovirusproteinase in the sample; and c) detecting the specific binding of theantibody to the adenovirus proteinase, wherein specific binding of theantibody indicates the presence of the adenovirus proteinase in thesample.

Immunospecific anti-proteinase antibodies can be used to isolateadenovirus proteinases, for example, by affinity chromatography. Theycan also be used to study adenovirus virion maturation and structure,and particularly, the function of the adenovirus proteinase. Forexample, described herein is use of the α23K1 antiserum to identify theAd2 proteinase peptide, to study the processing of a virion component,to detect the Ad2 proteinase in radiolabeled virions (Example 16), todetermine the location of the proteinase in virions (Example 17), and toestimate the number of proteinase polypeptides per virion (Example 18).

In addition, antibodies can be raised against a peptide cofactor ofadenovirus proteinase activity. Such antibodies may be useful forinvestigating the function of the cofactor in activating adenovirusproteinase. Antibodies which neutralize the peptide cofactor may beuseful as antiviral agents against adenovirus.

EXAMPLES

The present invention will now be illustrated by the following examples,which are not intended to be limiting in any way.

1. Cells, Viruses, and Vital DNA

HeLa cells were grown in suspension culture in Joklik's modified MEMwith 5% bovine serum, or on plates in an atmosphere of 5% CO₂ inDulbecco's modified MEM with 10% bovine serum and without antibiotics.Wild type Ad2 and the mutant, H2ts1 (Weber, J. Virol. 17:462-471(1976)), were propagated in HeLa cells, as described previously(Anderson, et al., J. Virol. 12:241-252 (1973); Anderson, Virology111:263-269 (1981)), except that H2ts1 was grown at 34° C. Adenovirusvirions were purified by two bandings in pre-formed CsCl gradients,essentially as described previously (Pettersson etal., J. Mol. Biol.73:125-130 (1973)), except that infected cells were lysed in isotonicbuffer containing 0.5% Nonidet-P40 (NP-40), and virions were purifiedfrom the low-speed supernatant. Wild type Ad2 and Ad12 viruses can beobtained from the American Type Culture Collection (Rockville, Md.).Adenoviral DNA was isolated as described (Anderson etal., J. Virol.48:31 (1983)).

2. Bacterial Cells, Plasmids, and Plasmid Construction

T7 expression vectors, such as pET-1, pET-3, and pET-12 are availablefrom Novagen, Inc. (Madison, Wis.). Vectors pET-1 and pET-3 and the hoststrain BL21(DE3) are described by Rosenberg et al. (Gene 50:125-135(1988)). The pET-12 vectors are similar to pET-1 vectors, but theycontain a segment encoding the signal peptide sequence of the E. coliouter membrane protein T (OmpT) in place of the amino-terminal fragmentof T7 gene 10 (Studier et al., Methods in Enzymology 185:60-89 (1990);Grodberg et al., Nucleic Acids Res. 16:1209 (1988)).

E. coli B strain BL21(DE3) expresses T7 RNA polymerase under control ofthe lac regulatory elements (Rosenberg et al. (1988) supra). It alsolacks the OmpT protein, but has a functional outer membrane signalpeptidase.

E. coli strain DH-1 was from D. Hanahan (Cold Spring Harbor Laboratory).Proteinase expression plasmids were propagated and maintained innonexpressing host strains (strains which do not express the T7 RNApolymerase), such as DH-1, to minimize the selection of variants thatare not capable of expressing the proteinase or that express inactiveproteinase (Hanahan, J. Mol. Biol. 166:557-580 (1983)).

The adenovirus proteinase expression plasmids and their predicted geneproducts are summarized in Table 2.

In order to construct plasmids encoding the Ad2 proteinase, DNAcontaining the open reading frame of the Ad2 proteinase (SEQ ID NO: 1)was excised from a preparation of virus DNA and inserted into abacterial plasmid, using standard cloning techniques. Adenovirus DNAsequences flanking the initiation and termination codons were removed,and recognition sites for the NdeI and SalI restriction enzymes werecreated 5' of the initiation codon (see FIG. 2). These restriction sitesfacilitated insertion of the proteinase coding sequence into theexpression cassette of the pET-12 bacterial expression vector. The NdeIrestriction site permitted placing the proteinase initiation codon atthe correct distance (about 10 bp) from the ribosome recognition site(or Shine-Dalgarno sequence) in the pET-12 vector to obtain efficientprotein synthesis (see Rosenberg et al., Gene 50:125-135 (1988)).

The Ad2reading frame (SEQ ID NO: 1) corresponds to nucleotides 21,781 to22,445 of the nucleotide sequence of the Ad2 genome (Yeh-Kai et al.,1983 supra; Roberts et al., in Adneovirus DNA: The Viral Genome and ItsExpression, W. Doerfler (ed.), Nijhoff, Boston, pp. 1-51 (1986)). Thecomplete sequence of the Ad2 genome is available from Genbank and othermolecular sequence databases.

Plasmid pCA93a contains the PvuII fragment of the Ad2 genome, extendingfrom nucleotide 21,769 to 23,386, cloned with BamHI linkers into theBamHI site of pBR322. The PvuII fragment contains the Ad2 proteinasecoding sequence (SEQ ID NO: 1).

Plasmid pT7AD23K1 was constructed by inserting the BamHI to EcoRVfragment of pCA93a (including Ad2 nucleotides 21,769 to 22,667) betweenthe BamHI and the EcoRV sites of the bacterial expression vector pET-1a.pT7AD23K1 encodes a fusion protein; it contains the Ad2 proteinasereading frame inserted behind a 12 codon segment of bacteriophage T7gene 10 (the gene for the major capsid protein).

Plasmid pT7AD23K2 contains the same Ad2 DNA fragment as pT7AD23K1 butcloned between the BamHI and EcoRV sites of the expression vectorpET-12b. It encodes a fusion protein in which the Ad2 proteinase has thesignal peptide sequence of the E. coli outer membrane protein T (OmpT)attached at its amino terminus. The OmpT signal peptide sequence directsthe fusion protein through the E. coli plasma membrane, where it iscleaved between amino acids Ala₂₀ and Ser₂₁ by a membrane-associatedsignal peptidase (FIG. 2; SEQ ID NO: 10).

Plasmid pT7AD23K5 (FIG. 1A) is similar to pT7AD23K2 but has the SalI toEcoRI linker sequence just before the proteinase translation initiationcodon removed. pT7AD23K5 encodes an OmpT signal peptide-Ad2 proteinasefusion protein (FIG. 2). The inserted Ad2 fragment in pT7AD23K5 wascopied from plasmid pT7AD23K2 using the polymerase chain reaction (PCR)technique and two primer oligonucleotides, one sense-strand primer, 5'CCCGTCGACCCATATGGGCTCCAG 3' (SEQ ID NO: 22), which is similar to thecoding sequence near the proteinase initiation codon, and a secondanti-sense strand primer, 5' GGCCCTTTCGTCTTCAAG 3' (SEQ ID NO: 23),which is similar to the opposite strand at a site just distal to theEcoRI site of pBR322. The first primer has a SalI site (G/TCGAC)incorporated near its 5' end, and an NdeI site (CA/TATG) at theinitiating methionine codon (nucleotide 21,778 of the Ad2 genome). Aftercleavage with SalI and EcoRI, the PCR-produced fragment was ligated tothe EcoRI to SalI fragment of pET-12b, resulting in pT7AD23K5.

The prototype plasmid pT7AD23K6 was derived from pT7AD23K5 by removingthe small NdeI fragment containing the OmpT leader sequence (see FIG. 2;SEQ ID NO: 3). Thus, unlike its parent plasmid, pT7AD23K6 does notencode a fusion protein. In this construct, the initiation codon for theAd2 proteinase is immediately preceded by the nucleotides CAT; togetherwith the ATG initiation codon, this sequence forms a recognition sitefor the NdeI restriction enzyme (CATATG).

Plasmid pT7AD23K10 was derived from pT7AD23K6. It was constructed byreplacing the PstI to NdeI fragment of pT7AD23K6 with the equivalentfragment of pET-3c; it has the same proteinase reading frame aspT7AD23K6.

Plasmid pT7AD23K11 has a deletion of the codons for Glu₅-Gln-Glu-Leu-Lys-Ala-Ile-Val-Lys₁₃ (SEQ ID NO: 2) from the Ad2proteinase reading frame. It was constructed by PCR amplification ofpT7AD23K6 using a sense-strand primer, 5'CCCCATATGGGCTCCTCAGATCTTGGTTGTGGGCC 3' (SEQ ID NO: 24), which extendsfrom the NdeI site 3' to a point beyond the BglII restriction site inthe proteinase reading frame (see FIG. 1A), and the same anti-senseprimer as was used to make pT7AD23K5(SEQ ID NO: 23). The fragmentbetween the NdeI site and the KpnI site within the proteinase codingsequence was cloned into pT7AD23K6 cut with NdeI and KpnI.

pT7AD23K8 has a unique AflII site at codons 202-204 of the Ad2proteinase reading frame. This plasmid was constructed by PCRamplification of the proteinase reading frame from pT7AD23K6 using asense primer with a sequence upstream of the proteinase initiationcodon, 5' TAATACGACTCACTATAGGGAGA 3' (SEQ ID NO: 25), and a downstreamanti-sense primer containing AflII and BamHI sites, 5'CTTGGATCCATTATTTTTACATGTTCTTAAGGTGACAA 3' (SEQ ID NO: 26). The amplifiedfragment was cloned into a pET-3c vector at the NdeI and BamHI sites.

pT7AD23K13 has a nine-amino acid addition, GHHHHHHNM, to the wild typeAd2 proteinase carboxy-terminus. This plasmid was derived frompT7AD23K8. A double-stranded DNA cassette containing the nine codonsbetween an AflII and a BamHI site was formed by annealing two oligomers:a sense strand oligomer, 5'TTAAGAACATGGGTCACCACCACCATCACCATAACATGTAAAAATAATG 3' (SEQ ID NO: 27),and a complementary antisense strand oligomer, 5'GATCCATTATTTTTACATGTTATGGTGATGGTGGTGGT-GACCCATGTTC-3' (SEQ ID NO: 28).The double-stranded cassette was then cloned into a pT7AD23K8 vectorfragment from which the 22 bp AflII-BamHI fragment had been removed.

Plasmids encoding the Ad12 proteinase were constructed similarly, exceptthat the Ad12 proteinase reading frame was copied directly from apreparation of Ad12 viral DNA (Strain Huie) using polymerase chainreaction (PCR) techniques. Amplification was performed using a senseprimer for the N-terminus: ##STR1## and an antisense primer for theregion beyond the carboxyterminus: ##STR2## Using the restriction sitesin the primers, the Ad12 proteinase coding sequence was cloned in-framewith the OmpT leader sequence in the pET-12 vector to make pT7AD23K15.pT7AD23K16 was then derived from pT7AD23K15 by removing the NdeIfragment which contains the OmpT leader sequence.

The Ad12 coding sequence (SEQ ID NO: 5) corresponds to nucleotides 127to 809 of the published sequence of the Ad12 proteinase (Houde andWeber, Nucleic Acids Res. 16:1795 (1988)). The complete sequence ofadenovirus 12 has been determined (Genbank AT12CGA). The coding sequencefor the Ad12 proteinase is contained within nucleotides 20,525 to21,145.

The recombinant DNA procedures used in plasmid construction have beendescribed (Maniatis et al., Molecular Cloning: a Laboratory Manual, ColdSpring Harbor Laboratory, N.Y. (1982)). PCR was performed with Taqpolymerase according to the instructions supplied by Cetus, Inc.Oligonucleotide primers were prepared using a Microsyn 1450oligonucleotide synthesizer manufactured by Systec, Inc.

3. Expression of Recombinant Proteinases in E. coli

BL21(DE3) cells were transformed with each of the above-describedplasmids, and transformants were selected for ampicillin resistance asdescribed (Maniatis et al., 1982 supra). Cultures of transformants weregrown to mid-log phase (about 5×10⁸ bacteria per ml) at 37° C. inL-broth or in M9 medium containing 40 μg ampicillin. IPTG was added to0.4 mM to induce expression of the proteinass, and the temperature waslowered to 30° C. After incubation for two to six hours at 30° C. inIPTG, the culture was harvested by centrifugation, washed once withSuspension Buffer (50 mM Tris-HCl, pH 8.0, 5 mM EDTA, 1 mMmercaptoethanol, 4% glycerol) as described (Rosenberg etal., 1988supra). Harvested cultures may be stored frozen in Suspension Buffer at-20° or -70° C.

To prepare soluble extracts containing the proteinase, a harvestedculture is resuspended in 10 ml Suspension Buffer per 100 ml of initialculture. The bacterial suspension was put through three cycles offreezing in a dry ice-ethanol bath and thawing. The suspension was thenincubated with 100 μg/ml lysozyme for 15 minutes at 37° C. to lyse thebacteria. After addition of MgCl₂ to 10 mM and DNAse I to aconcentration of 100 μg/ml, the suspension was incubated for another 15minutes at 37° C. to degrade DNA and reduce the viscosity. Soluble andinsoluble components were separated by centrifugation at 10,000×g for 20minutes at 4° C. or at 12,000×g (in microcentrifuge tubes) for 10minutes at room temperature.

FIG. 3 shows the expression of plasmids pT7AD23K5 and pT7AD23K6 inBL21(DE3) cells after induction. Log-phase cultures of BL21(DE3) (lanesc and f), pT7AD23K5/BL21(De3) (lanes d, g, and h), andpT7AD23K6/BL21(DE3) (lanes e, i, and j) were labeled for 5 minutes with[³⁵ S]-methionine at 1 (lanes g and i) and 2 hours (lanes c-f, h, and j)after IPTG induction. Bacterial extracts were prepared immediately afterlabeling and run on SDS-polyacrylamide gels. Shown are a CoomassieBlue-stained SDS-polyacrylamide gel (left) and an autoradiogram (right)of the gel. Arrows mark the positions of the induced proteinase fusionproteins. Also shown are the polypeptides of purified Ad2 (lane a) andH2ts1 (lane b) virions.

As shown in FIG. 3, the recombinant proteinase quickly became the mostrapidly synthesized polypeptide after induction, and rapid synthesiscontinued for more than 2 hours after induction (lanes f-j), even withpT7AD23K6, which makes active Ad2 proteinase. As judged from theComassie Blue-stained gel, plasmid pT7AD23K5 produced nearly equalamounts of a 25 kDa (23K5a) polypeptide and a 23 kDa (23K5b) polypeptide(lane d). This suggests that the OmpT signal peptide sequence is cleavedfrom a portion of the pT7AD23K5 expression product. Pulse-chaseexperiments confirmed that a portion of the 25 kDa polypeptide wasrapidly processed to the 23 kDa product. However, the 25 kDa polypeptidethat was not processed within about 5 minutes of synthesis was stable,even several hours after synthesis. The sequence analysis summarized inTable 2 shows that the 23 kDa polypeptide begins with serine₂₁. Similarresults were obtained from expression of pT7AD23K2 (Table 2).

The expressed proteinase polypeptides were then tested for solubility.Induced bacteria were harvested and lysed with lysozyme-EDTA, and10,000×g supernatants were prepared. In each case, the majority of theproteinass polypeptide was found in the 10,000×g pellet. When pelletfractions were analyzed by SDS-polyacrylamide gel electrophoresis in theabsence of a reducing agent, only a small fraction of the proteinasspolypeptides entered the stacking gel, showing that most of thebacterially synthesized proteinass was misfolded and crosslinked throughdisulfide bonds. This finding was true for both pT7AD23K5 products(23K5a and 23K5b) as well as for the 23K6 polypeptide.

4. Assay of Adenovirus Proteinass Activity in Crude Extracts

Adenovirus proteinass activity was monitored by the cleavage of [³⁵S]-methionine-labeled major core precursor (pVII) essentially asdescribed (Bhatti and Weber, Biochem. Biophys. Res. Comm. 81:973-797,(1978)). The proteinase substrate was prepared from Ad2 tsl-infectedHeLa cells grown at 39° C. and labeled with [³⁵ S]-methionine (200μCi/plate) from approximately 28 to 30 hours after infection. Labeledcultures were harvested, washed twice in Phosphate Buffered Saline(PBS), resuspended in 1.0 ml of 10 mM sodium phosphate buffer, pH 7.4,per plate, and sonicated for 40 seconds using a water-cooled sonicatorhorn (Branson Sonic Power Co., Danbury, Conn.). The extract was thencentrifuged at 12,000×g for 10 minutes, and the pellet was resuspendedin 10 mM phosphate buffer.

Extracts of Ad-infected cells, harvested 40 hours after infection at 37°C. were used as a source of viral proteinass. Harvested cultures werewashed twice with PBS, resuspended in 10 mM phosphate buffer, frozen andthawed once, and centrifuged at 12,000×g for 10 minutes. Pellets wereresuspended in 1.0 ml phosphate buffer, pH 7.4, per 10⁶ infected cellsand sonicated 4×10 seconds; samples were stored at -70° C. Bacterialextracts were prepared by lysozyme-EDTA treatment of cultures harvested2 hours after IPTG induction.

Assays were performed by mixing equal volumes of [³⁵ S]-labeledsubstrate and test extract and incubating at 37° C. At different times,25 μl samples were removed, mixed with 25 μl of SDS Sample Buffer,heated to 90° C., and analyzed by SDS-polyacrylamide gel electrophoresisand autoradiography as described (Anderson et al., J. Virol. 12:241-252(1973).

5. Activity of Recombinant Adenovirus Proteinases

Recombinant proteinase polypeptides were assayed for proteinase activityby incubating whole-cell extracts of BL21(DE3), pT7AD23K5/BL21(DE3), andpT7AD23K6/BL21(DE3), prepared as described above, with extracts of [³⁵S]-methionine-labeled Ad2 virion precursor polypeptides. Incubation ofthe labeled extract at 37° C. for up to 20 hours, alone or with anextract prepared from uninfected HeLa cells, produced little change inthe pattern of labeled polypeptides.

FIG. 4 is an autoradiogram of an Ad2 proteinase assay for the processingof pVII by wild type and recombinant Ad2 proteinases. Proteinase assayswere performed as described above. An extract prepared from HeLa cellsharvested 40 hours after infection with wild type Ad2 (lane b) served asa source of authentic proteinase. Bacterial extracts (unfractionated)were prepared from untransformed BL21(DE3) (lane e), pT7AD23K5/BL21(DE3)(lane d), and pT7AD23K6/BL21(DE3) (lane c) 2 hours after IPTG induction.Samples were removed at different times after induction and analyzed bySDS-polyacrylamide gel electrophoresis; the autoradiogram in FIG. 4shows the assay at a 90 minute time point. The positions of several Ad2virion components are given on the right; [³⁵ S]-methionine labeled wildtype Ad2 virions were applied to lane a.

Incubation with extracts of wild type Ad2-infected HeLa cells caused therapid disappearance of the major core protein precursor, pVII (lane b),and of L2-79R, the precursor to Mu (Anderson, et al., Virology172:506-512 (1989)). Simultaneously, a polypeptide the size of componentVII appeared. Mu and its precursor were not resolved on the gel shown inFIG. 4. Processing of pVI and pVIII was not apparent.

Incubation of the [³⁵ S]-methionine-labeled Ad2 polypeptides withextracts prepared from BL21(DE3) (lane e) or from pT7AD23K5/BL21(DE3)(lane c) produced little change in the polypeptide pattern, even after a20 hour incubation. Two unidentified polypeptides, with a mobilitysimilar to component V, disappeared when incubated with E. coliextracts; these components were stable when incubated with infected oruninfected HeLa extracts.

Incubation with an extract prepared from pT7AD23K6/BL21(DE3) causedrapid processing of the precursor, pVII (lane d) and L2-79R (pMu). Theamount of processed VII increased as the amount of pVII decreased. By 2hours virtually all of pVII had been converted to VII. Processingactivity in the bacterial extracts was stable for only about 2 hours at37° C. As judged by the pVII assay, 23K6 proteinase activity wasdistributed equally between soluble and insoluble fractions of the E.coli extract, despite the fact that the majority of the 23K6 polypeptidewas in the insoluble fraction.

To confirm that processing by the E. coli expressed proteinase wasaccurate, component VII was purified from a 2 ml assay that wasincubated with the pT7AD23K6/BL21(DE3) extract for 2 hours and thesequence of its amino terminus was determined. The expectedaminoterminal sequence of component VII (Sung et al., J. Biol. Chem.258:8266-8272 (1983)),Ala-Lys-Lys-Arg-Ser-Asp-Gln-His-Pro-Val-Arg-Val-Arg₁₃ (SEQ ID NO: 31),was observed indicating that pVII had been correctly processed by therecombinant 23K6 proteinase.

Virion component VII was purified from the in vitro cleavage reaction byphosphocellulose chromatography in 40 mM methylamine phosphate, pH 5.6,6M urea as described (Hosokawa et al., J. Virol. 17:924-934 (1976)).Component VII eluted between 0.4 and 0.8M NaCl. Partially purifiedvirion-derived proteinase and recombinant proteinase polypeptides canalso obtained by this method. The virion proteinase elutes fromphosphocellulose between 0.1 and 0.4M NaCl.

Although no proteinase activity was observed with extracts prepared frompT7AD23K5/BL21(DE3) 2 hours after induction (FIG. 4, lane c), processingactivity was observed in extracts from uninduced cells grown tostationary phase. Extracts from uninduced pT7AD23K1- andpT7AD23K2-transformed cells grown to stationary phase also exhibitedproteinase activity. Extracts from uninduced, stationary phase cellswhich express the proteinase fusion proteins 23K5, 23K1, and 23K2 hadless proteinase activity than similarly prepared extracts from cellsexpressing 23K6. No processing activity was detected in extracts fromcells expressing the deletion variant 23K11 after either IPTG inductionor growth to stationary phase.

6. Amino-Terminal and Tryptic Peptide Sequencing Methods

Purified (to near homogeneity), carboxymethylated, recombinantproteinases obtained as described in Example 3 were resuspended in 0.1MNH₄ HCO₃, and incubated with approximately 1/50 weight trypsin at 37° C.for 6 hours. The vacuum-dried digest was resuspended in 20% formic acid,clarified by centrifugation at 12,000×g for 10 minutes, and applied to aC8 reverse-phase column (Aguapore RP-300, 4.6×220 mm from PierceChemical co., Rockford, Ill.) equilibrated in 0.1% trifluoroacetic acid(TFA). Peptides were eluted with a linear gradient of acetonitirile in0.1% TFA at 1 ml/minute; the column was monitored at 214 nm, and 1 mlfractions were collected.

Tryptic peptide and amino-terminal sequences were determined asdescribed (Anderson, Genetic Engineering: Principles and Methods, Setlowet al. (eds.), 4:147-167 (1982); Lees-Miller and Anderson, J. Biol.Chem. 264:2431-2437 (1989); Lees-Miller and Anderson, J. Biol. Chem.264:17,275-280 (1989) using an Applied Biosystems 470A "gas-phase"sequencer with a Model 120 on-line PTH analyzer and Hewlett-Packard3396A integrator (Applied Biosystems, Inc., Foster City, Calif.). Aminoacid compositions were determined using the Aminoquant systemmanufactured by Hewlett-Packard after hydrolysis of samples with 6N HClin vacuo at 110° C.

7. Peptide Sequence Analysis of Recombinant Proteinases

The amino-terminal sequence obtained for each recombinant proteinase isindicated (by underlining) in Table 2. In each case analyzed, theamino-terminal sequence obtained was that expected from the structure ofthe plasmid encoding the recombinant proteinase. Exceptions were theexpression products of pT7AD23K6, pT7AD23K8, pT7AD23K10, and pT7AD23K16,which had a mixture of proteinase amino-termini with and without theinitiating methionine. The relative amounts of the two aminoterminidiffered from experiment to experiment for each expression product.

Amino-terminal sequence analysis allowed prediction of the exact size ofeach recombinant proteinase (Table 2). This prediction assumes that thestructure of the cloned reading frame is correct and that no processingoccurred at the carboxyterminus. To confirm these assumptions, thestructure of 23K6 was analyzed in greater detail.

About 100 μg of bacterially produced 23K6 polypeptide were labeled with[³⁵ S]-cysteine, carboxymethylated to disrupt disulfide bonds, and thendigested with trypsin. The peptides that were soluble in 20% formic acidwere applied to a C8 reverse phase column equilibrated in 0.1% TFA, andeluted with a gradient of acetonitrile. FIG. 5 shows a chromatogramindicating the acetonitrile gradient (dotted line) and the elutionprofile as detected at 214 nm (solid line) or by scintillation counting(short dashed line). Six tryptic peptides with eight cysteinesdistributed among them are predicted from the Ad2 proteinase amino acidsequence (SEQ ID NO: 2). The prominent peaks are labeled with letters.The chromatogram shows that while eight unlabeled peptides were detectedby absorption at 214 nm, only three peaks of radioactivity were found inthe chromatogram and only a quarter of the radioactivity was solubleafter trypsin digestion, suggesting that some of the radiolabeledcysteines were in hydrophobic tryptic peptides. This was confirmed byradiochemical sequence analysis of the insoluble fraction after trypsindigestion, indicating the presence of Cys₁₇ and/or Cys₆₇, Cys₁₂₂,Cys₁₂₆, and Cys₁₂₇ in the insoluble fraction. The three [³⁵S]-cysteine-containing peaks and several of the unlabeled trypticpeptides were analyzed for amino acid content and amino-terminalsequence.

Fractions 6 and 7 contained three expected dipeptides corresponding toSer-Lys₆₅, Leu-Lys₈₁, and Asn-Met₂₀₄. Asn-Met is the predictedcarboxy-terminal tryptic dipeptide of the Ad2 proteinase.Carboxymethylcysteine was not detected in fraction 65 or 7 by amino acidanalysis, nor was a cysteine-containing peptide observed after sequenceanalysis. The radioactivity in fractions 6 and 7 may have resulted fromunincorporated [³⁵ S]-cysteine.

[³⁵ S]-Cysteine-labeled peptides were detected in fractions 37 and 42.Sequence analysis identified the peptide Cys-Ile-Thr-Leu-Glu-Lys₁₀₉ (seeSEQ ID NO: 2) in fraction 37 (peak F), andSer-Ala-Thr-Ser-Phe-Cys-His-Leu-Lys₂₀₂, the carboxy-terminalcysteine-containing peptide, in fraction 42 (peak G). Other identifiedinternal tryptic peptides included:Gln-Val-Tyr-Gln-Phe-Glu-Tyr-Glu-Ser-Leu-Leu-Arg₉₃ (peak I);Ser-Ala-Ile-Ala-Ser-Ser-Pro-Asp-Arg₁₀₃ (peak C);Asn-Gln-Glu-Gln-Leu-Tyr-Ser-Phe-Leu-Glu-Arg₁₈₀ (peak H);His-Ser-Pro-Tyr-Phe-Arg-Ser-His-Ser-Ala-Gln-Ile-Arg₁₉₃ (peak B); and therelated peptide His-Ser-Pro-Tyr-Phe-Arg₁₈₆ (peak E). Peak D is a peptidethat extends from Ser₁₈₇ through the carboxy-terminus of the proteinase.(Peak C was not identified; peaks J and K have not been analyzed.)

In summary, amino-terminal and tryptic peptide sequence analysistogether directly confirmed one-third of the predicted sequence of the23K6 proteinase (FIG. 6). Peptide analysis therefore supports theconclusion that 23K6 is exactly the 204 (or 203 without the initialmethionine) amino acid Ad2 proteinase predicted from the nucleotidesequence of the Ad2 genome (SEQ ID NO: 1).

8. Cloning and DNA sequencing of Ad12

Ad12 DNA was cleaved with BamHI and the resulting fragments were clonedinto the BamHI site of plasmid pBR322 by standard techniques.(Sambrooket al., 1989). Plasmid pPF2109 carries the Ad12 BamHI J fragment,pPF2112 carries the BamHI I fragment, and pPF2137 carries the BamHI Ffragment.

The DNA sequence was obtained by the dideoxynucleotide triphosphateterminator method using Sequence version 2.0 (U.S. Biochemical,Cleveland, Ohio) and oligonucleotide primers. Both strands of thereported sequence were determined. Where required, band compressionswere resolved by performing parallel reactions with dITP.

9. Preparation and Yield of Purified Activatable Recombinant Ad2Proteinass

Growth and induction of plasmid-containing BL21 (DE3) strains,harvesting, and lysis were described [Anderson, C. W., Virology, 177;259(1990)] [Studier, W. F. et al., Methods Enzymol. 185;60 (1990)] exceptthat the incubation temperature for growth was 30° C. instead of 37° C.After clarification by centrifugation at 10,000 g for 10 min, the lysatefrom 100 ml of culture was applied to a DEAr column (˜3-ml bed volume)equilibrated in 50 mM Tris-HCl, pH 8.0, 1 mM DTT, and the flow-throughwas collected. Pooled flow-through fractions were dialyzed briefly (˜2h) against 50 mM Tris-HCl, pH 8.0, 100 mM NaCl (Zn-column buffer) toremove EDTA and then applied to an ˜2-ml (per 100 ml of culture) columnof iminodiacetic (IDA or chelating) Sepharose (Pharmacia-LKB, Inc.)saturated with Zn²⁺ [Hochuli, E. et al., J. Chromatogr, 411;177 (1987)]and equilibrated in the same buffer. After washing with 5 column volumesof Zn-column buffer containing 25 mM imidazole, then 5 volumes of 50 mMTris-HCl, pH 8.0, 1.0M NaCl, and finally 1-2 volumes of Zn-column bufferwithout imidazole, the proteinase was eluted with 25 mM EDTA, pH 8.0,containing 100 mM NaCl. The EDTA-eluted proteinase was concentrated bycentrifugation using a Centricon 10 concentrator (Amicon, Inc.), washedonce or twice by centrifugation with 25 mM Tris-HCl, pH 8.0, containing2.5 mM DTT and 10 mM octoglucoside (EP Assay Buffer), and stored at -70°C.

The yield of purified proteinase was determined with the Bio-Raddye-binding assay using BSA as the standard. HEP1DBP was purified frompT7HEP1DBP/BL21(DE3) cells by the same procedure. In some cases,cultures were labeled with [³⁵ S]methionine after induction as described[Anderson, C. W., Virology, 177;259 (1990)].

For cation-exchange chromatography on MonoS, the column was equilibratedin 25 mM Hepes, pH 7.5, 0.2 mM EDTA, and 0.1 mM DTT, and elution waswith a linear gradient of KCl in the same buffer. Gel filtration onSuperdex 55 HR30/10 was in 25 mM Hepes, pH 8.2, 0.02% NP-40, and 0.2 mMDTT. Buffers were applied using the fast protein liquid chromatography(FPLC) system (Pharmacia-LKB) at room temperature.

A 100 ml culture yields approximately 200 μg of adenovirus proteinasepurified to near homogeneity. The eluted proteinase is highly active inthe presence of cofactors, even in the absence of divalent metal ions,such as zinc. Induced cultures of E. coli transformed with pT7AD23K6 canyield 1 to 2 mg of purified, active recombinant Ad2 proteinase per literof culture.

10. Production of Activatable Recombinant Proteinase in a BaculovirusVector/Insect Cell Expression System

A baculovirus vector (vNPVAd2EP) was made which expresses the Ad2proteinase. The Ad2 coding sequence from pT7AD23K8 was cloned into abaculovirus transfer vector, pETL, and transferred to the nuclearpolyhedrosis baculovirus by transfection and plaque purification; theAd2 proteinase gene replaces the polyhedron protein gene in the vector.Recombinant baculovirus vNPVAd2EP was constructed as follows:

1. A DNA fragment containing the proteinase gene from pT7AD23K8 wasproduced by PCR using the primers:

BNL#937 N-Terminal sense-strand PCR primer for Ad2 proteinase. Thisprimer contains an NdeI site at the proteinase initiation sequence andis homologous to the first 13 nucleotides of the Ad2 proteinase gene.

BNL#937 5' TTTTGCTAGCATGGGCTCCAGTG 3' (SEQ ID NO: 38)

BNL#430 This primer is homologous to sequence at the EcoRI site inpBR322 and in pET vectors. It may be used in combination with pET vectorpromoter primers, or other sense strand primers, to copy by PCR genesinserted into the expression site of pET vectors. The copied sequencewill include an EcoRI site corresponding to that in pBR322.

BNL#430 5' GGCCCTTTCGTCTTCAAG 3' (SEQ ID NO: 34)

2. The PCR amplified fragment from pT7AD23K8 was cleaved with NheI andBamHI and the proteinase gene fragment was purified by agarose gelelectrophoresis.

3. The pETL vector was cleaved with NheI and BamHI and was purified.

4. The proteinase gene from #2 was ligated with the cleaved vector, andthe ligation products were used to transform DH5. Plasmid DNA fromseveral independent colonies' was characterized by restriction analysisand four, designated #239A, #239B, #239C and #239D, were selected forfuture use.

5. DNA from two of these were mixed (separately) with DNA from wild typebaculovirus (ACNVP) from P. Tegtmeyer, State University of New York,Stony Brook; the DNA is also available commercially from BRL andInvitrogen). The mixture was used to transfect Sf9 cells by the calciumphosphate technique.

6. After incubation to produce recombinant virus, the lysate was plaquedon Sf9 cell monolayers and overlayed with agar containing Bluo-Gal (BRLCat. No. 5519UA/UB according to recommendations provided by BRL(Baculovirus Plaque Assay and Purification, GIBCO/LTI, 2/91). Wellisolated blue colonies were picked and the virus in these was amplifiedby infection of Sf9 cells. GIBCO BRL Life Technologies, Inc., 8400Helgerman Court, Gaithersburg, Md. 20877; (Corporate Headquarters).

7. The resulting virus was tested for expression of proteinase byinfection of Sf9 cells. After about 48 hr, the infected cells wereharvested, and the proteins in these extracts were analyzed bySDS-polyacrylamide gel electrophoresis and Western blotting. Plaqueswere chosen for further purification based on the amount of proteinaseexpressed, as detected by Western blotting using the 23K1 polyclonalserum, and the (low) level of polyhedron protein (from contaminatingwild type virus).

8. Recombinant virus was purified by two additional rounds of plaquepurification following standard virology practices, and a high titerstock was produced.

9. The stock was used to infect Sf9 cells, and the expression ofproteinase polypeptide was confirmed by Western blotting experiments.

10. An extract of Sf9 cells was prepared by freeze-thaw lysis, andproteinase was prepared from the soluble fraction by DEAE- andzinc-affinity chromatography, as described for purification ofproteinase from bacterial extracts.

Recombinant Ad2 proteinase was partially purified from Sf9 cellsinfected with the recombinant baculovirus by the same procedure forpurifying proteinase from bacteria, as described in Example 9. Therecombinant proteinase, which was about 5% pure, was shown to have aspecific activity equivalent to that of bacterially-produced proteinaseusing the fluorescence assay, Ad2 DNA and H2tsl virions to providecofactor.

Methods, baculovirus vectors, and SF9 cells have been described(Summers, Max D. and Smith, Gale E., A Manual of Methods for BaCulovirusVectors and Insect Cell Culture Procedures, Texas AgriculturalExperiment Station Bulletin No. 1555, Texas Agricultural ExperimentStation and Texas A&M University College Station, Tex. 77843-2475, (409)845-9730 (1988); Chen et al., J. Virology 65(10):5131-5140 (1991);Vialard et al., J. Virology 64(1):37-50 (1990)). pETL can be obtainedfrom Dr. Christopher D. Richardson, Biotechnology Research Institute,6100, avenue Royalmount, Montreal, Quebec, Canada H4P 2R2.

11. Fluorescent Assay for Adenovirus Proteinase Activity

Assays were performed in 400 μl of Assay Buffer (50 mM Tris-HCl, pH 7.4,25 mM NaCl, 10 mM octylglucoside, and 1 mM dithiothreitol). Theconcentration of the fluorogenic substrate, (Leu-Arg-Gly-Gly-NH)₂-rhodamine was 5 μM. When present, the number of disrupted virusparticles was 10¹⁰ and the amount of recombinant proteinase was 0.12mAU₂₈₀ nm. (mAU₂₈₀ : One thousandth the absorbance of light at 280 nmpassing through a 1 cm pathlength. Typical proteins give an opticaldensity at 280 nm of between 0.5 and 2 when dissolved at a concentrationof 1 mg/ml. The extinction coefficient for 23K6 has not been determinedexperimentally, but theoretical calculations suggest that a 1 mg/mlsolution of pure 23K6 should have an optical density of about 1). After30 minutes at 37° C., a 360 μl aliquot of the reaction was added to 340μl of Assay Buffer minus octylglucoside, and the increase influorescence was measured. The excitation wavelength was 492 nm and theemission wavelength was 523 nm, both with a bandwidth of 5 nm. Thechange in fluorescence, ΔF, is the magnitude of the fluorescence fromthe sample minus the magnitude of the fluorescence from an identicalsolution without enzyme.

Disrupted virus was obtained as follows: Twice CsCl-banded virus wasdialyzed against 10 mM Tris-HCl, pH 8.0, 1 mM EDTA and centrifuged at100,000×g for 1 hour. The pellet was suspended in 10 mM Tris-HCl, pH6.8, containing 20% (v/v) glycerol and, after three 10 second bursts ofsonication, was stored at -20° C. The fluorogenic substrate wassynthesized and purified at Brookhaven National Laboratory by Dr. WalterMangel, using methods similar to those previously described by Dr.Mangel. These methods are described in two U.S. Patents (U.S. Ser. No.4,557,862 entitled "Rhodamine derivatives as fluorogenic substrates forproteinases" by Mangel, W. F., Leytus, S., and L. Helhado; issued Dec.10, 1985; U.S. patent application 780,552; "Novel rhodamine derivativesas fluorogenic substrates" by Mangel, W. F., Leytus, S., and L. Helhado;filing date Sep. 24, 1985) and in other publications by Mangel andcoworkers.

DNase-treated disrupted virus was obtained by incubating 2×10¹⁰disrupted virions in 20 μl containing 0.1M NaAc, pH 5.0, 5 mMMgCl₂, and55 μg/ml DNase I for 4 minutes at 25° C. Then, EDTA to 23 mM anddithiothreitol to 2.3 mM were added, and the reactions were heated at56° C. for 1 minute to inactivate the DNase.

For the assays shown in FIG. 8, the DNase reactions were diluted by theaddition of 380 μl Assay Buffer containing the substrate, the proteinaseand either 2×10¹⁰ molecules of Ad2 DNA (+) or no DNA (-). After 30minutes at 37° C. 360 μl of the reactions were added to 340 μl AssayBuffer minus octylglucoside and the increase in fluorescence wasmeasured. The assays in (B) and (C) were identical to those in (A)except that in (B) H2tsl virus was added after the DNase was inactivated(i-DNase) and in (C) no DNase was present. In (D) recombinant proteinaseplus 10¹⁰ molecules of Ad2 DNA were preincubated for 10 minutes at 37°C. before adding substrate.

Plasmin-treated disrupted virus was obtained by incubating 4×10¹⁰disrupted virons in 20 μl of 10 mM Tris-HCl, pH 8.0, 1 mM EDTA, and 33nM plasmin for 4 minutes at 37° C. Dithiothreitol was added to 2 mM andthe solution heated at 56° C. for 1 minute to inactivate the plasmin.

For the assay shown in FIG. 9A, virions and proteinase were preincubatedfor 10 minutes at 37° C. before adding substrate. The assay in (C) wasidentical to that in (B) except the plasmin incubated with disruptedvirus had previously been inactivated (i-plasmin) by heating to 56° C.in the presence of 2 mM dithiothreitol.

12. Purification and Characterization of the Peptide Cofactor

Purification of the peptide cofactor was performed in two steps. In thefirst step, Ad2 virus (about 5.8×10¹² virions), purified twice bydensity gradient centrifugation, was suspended in 0.8 ml of 10 mMTris-HCl, pH 8, 1 mM EDTA and 10% pyridine. After 1 hour at 25° C., thesolution was centrifuged at 12,000×g for 6 minutes. The pellet wasresuspended in 0.8 ml of 0.01 M Hepes, pH 8, and centrifuged at 12,000×gfor 6 minutes. The pellet was resuspended in 0.8 ml of 0.01 M Hepes, pH8, 0.01M octylglucoside and 0.001M EDTA, and then centrifuged at 5,000×gin a Centricon-30until 90% of the liquid flowed through the membrane. Tothe liquid that was retained, the volume was increased to 0.8 ml withNH₄ C₂ H₃ O₂ such that its concentration was 1M. The Centricon-30 wasagain centrifuged at 5,000×g until greater than 90% of the liquid flowedthrough the membrane. Assays were performed in the presence of therecombinant proteinase and in the absence or presence of 778 ng/ml Ad2DNA.

In the second step, the flowthrough from the second Centricon-30 wasevaporated to dryness, dissolved in 0.1% trifluoroacetic acid, andapplied to a C₁₈ reverse phase column (Aquapore OD-300 7μ, 100 nm longwith a 2.1 mm diameter; Pierce Chemical Co., Foster City, Calif.). Theactivity was eluted by a linear gradient from 0-30% acetonitrile in 0.1%trifluoroacetic acid at a rate of 1%/minute.

Assays of fractions from peaks a, b, and c were performed (FIG. 11). Theamino acid sequences of the proteins in peaks a-c were determined in agas phase sequencer, as shown in FIG. 12 (amino acids 240-250 of SEQ IDNO: 15). The "?" at position 6 in this figure indicates a variable yieldof lysine. The two adenovirus proteinase consensus cleavage sequences inpVI are underlined, and the location of the peptide cofactor sequencebeginning at position 240 is printed in bold. The amino acid sequence ofpVI was from Roberts et al. (1986 supra).

The amino acid sequence of the peptide cofactor is consistent with thebiochemical data. The peptide cofactor was sensitive to plasmin, becauseit contains three arginine residues. The peptide was not in theflowthrough after the first Centricon-30 centrifugation, because it is avery basic protein and was probably bound to the viral DNA. High ionicstrength would dissociate it from the viral DNA, and thus, after thesecond Centricon-30 centrifugation, it was in the flowthrough. Beforethe second Centricon-30 centrifugation, fluorescence assays for thepeptide cofactor did not require Ad2 DNA, but after the centrifugation,there was an absolute requirement for the DNA. Consistent with thepeptide cofactor being a small protein are the observations that boilingfor 5 minutes did not irreversibly denature it, that at high ionicstrength it flowed through a Centricon-3, and when incubated in 5M urea,it rapidly regained activity upon dilution of the urea.

13. Preparation of Anti-Ad2 Proteinase Serum and Western Blot Analysisof Adenovirus Proteinase

Polyclonal antibody against Ad2 proteinase was prepared using the 23K1polypeptide as an immunogen. 23K1 is a proteinase fusion proteinconsisting of 12 amino acids of the T7 gene 10 protein fused to the Ad2proteinase. 23K1 fusion protein was produced from transformed BL21(DE3)cells as described in Example 3. 23K1 protein was solubilized from lysedbacterial pellets with SDS Sample Buffer and fractionated by preparativeSDS-polyacrylamide gel electrophoresis. Gels were stained briefly withCoomassie Blue, destained with 50% methanol and 10% acetic acid, andthen dried. Gel segments containing the proteinase polypeptide wererehydrated in phosphate-buffered saline (PBS), homogenized, and injectedintradermally or subcutaneously at approximately monthly intervals intothe backs of New Zealand White (female) rabbits, as described (Zorn andAnderson, J. Virol. 37:759:769 (1981)). Blood was withdrawn from the ear10 and 15 days after each injection; serum was separated from wholeblood by centrifugation.

For Western blot analysis, sample proteins were separated bySDS-polyacrylamide gel electrophoresis, then, electrophoreticallytransferred to nitrocellulose or to Immobilon PVDF (Millipore, Inc.,Bedford, Ma.) membranes at 80 V for 30 minutes in Transfer Buffer (25 mMTris-HCl, about pH 8, 192 mM glycine, 25% methanol) using a Bio-RadMini-gel transfer tank. Immunological detection was accomplishedfollowing manufacturer's suggested methods (Bio-Rad Richmond, Calif.).Immunological probing with α23K1 antibody was performed at a 1/200 to1/800 dilution of the unfractionated hyperimmune rabbit serum. Alkalinephosphatase-conjugated anti-rabbit IgG was used for the secondaryantibody.

14. Immunodetection of the Ad2 Proteinase

α23K1 antiserum was used to detect bacterially produced Ad2 proteinasesand viral Ad2 proteinases from purified wild type and mutant H2tslvirions and Ad2-infected HeLa cells. Ad2 virions were purified bybanding in CsCl gradients, as described by Anderson (Virology, 177:259,1990). Purified recombinant proteins were prepared by HPLC, as describedpreviously. Sample proteins were routinely applied to two parallelSDS-polyacrylamide gels. One gel was stained with Coomassie Blue, dried,and exposed to X-ray film to reveal the migration pattern of theradiolabeled polypeptides. The second gel was electrophoreticallytransferred to an Immobilon membrane and probed with α23K1 serum toreveal the position of the Ad2 proteinase polypeptides. The immunoblotwas then exposed to X-ray film to detect the [³⁵ S]-labeled Ad2 virionproteins in a control lane. To assist in aligning the immunoblot withthe Coomassie Blue-stained gel, small amounts of purified recombinantproteinases 23K5a, 23K5b, and 23K6, labeled with [³⁵ S]-methionine, wereanalyzed on each gel.

FIG. 14 shows the identification of the Ad2 proteinase polypeptide inisolated virions and Ad2infected HeLa cells on SDS-polyacrylamide gelelectrophoresis and Western immunoblots. Samples were analyzed bySDS-polyacrylamide gel electrophoresis on identical 10% gels: one gelwas stained with Coomassie Blue (A); the other gel waselectrophoretically transferred to an Immobilon membrane and probed withα23K1 rabbit serum (B). Lanes a and f show the HPLC-purified proteinasefusion protein products of plasmid pT7AD23K5 (23K5a and 23K5b weremixed). Lanes b and e show HPLC-purified 23K6. Lanes c and k showproteins from purified wild type Ad2 virions. Lanes d and l showproteins from purified Ad2tsl virions. Lanes g and h show thesupernatant and pellet fractions, respectively, of freeze-thaw lyseduninfected HeLa cells. Lanes i and j show comparable fractions ofAd2-infected HeLa cells harvested 40 hours after infection.

The Western blot (B) shows that the recombinant proteinases 23K6 (lanesb and e) and processed 23K5b (lanes a and f) have a mobilityindistinguishable from that of the virion-derived wild type Ad2proteinase (lanes c and k). A polypeptide of the same mobility wasdetected in Ad2-infected HeLa cells (lanes i and j), but not inuninfected cell extracts (lanes g and h). More Ad2 proteinase waspresent in the insoluble 12,000×g pellet (lane j) than in the soluble,low-salt supernatant fraction (.lane i). Comparison of the immunoblot,its autoradiogram, and the parallel Coomassie Blue-stained gel showedthat the viral Ad2 proteinase had a mobility during SDS-polyacrylamidegel electrophoresis intermediate between that of pVII and VII.

FIG. 15 shows Western blots of proteinases from Ad2 and H2tsl virions.Virion proteins were separated on a 17.5% SDS-polyacrylamide gel andtransferred to Immobilon. Identical filter sets were incubated overnightwithout rabbit antiserum, with pre-immune serum at 1/500 dilution (leftblot) and with hyperimmune α23K1 serum at 1/500 dilution (right blot).Samples shown are: (lane a) proteins from 4×10¹⁰ wild type Ad2 virions;(lane b) proteins from 5.3×10¹⁰ H2tsl virions; (lane c) purified 23K10(recombinant Ad2 proteinase); and (lane d) purified 23K11 (Ad2proteinase variant with amino-terminal deletion). The positions of Ad2virion components, determined from an autoradiogram of the immunoblot,are indicated at the right; 79R is the precursor to μ.

The mobility of the proteinase in H2tsl virions (lane f) wasindistinguishable from that in wild-type virions (lane e) and from therecombinant proteinase 23K10 (lane g). As expected, the recombinantproteinase variant 23K11 (lane h), which is only 194 amino acids longdue to a deletion in the aminoterminal region, migrated distinctlyquicker than the wild type proteinase.

No smaller immunoreacting polypeptides were detected in gels thatresolved virion proteins of less than 10 kDa (lanes e and f). Thissuggests that the Ad2 proteinase is not itself proteolyticallyprocessed.

The α23K1 antiserum reacted strongly with the purified recombinantproteinases produced in bacteria, even though these were barely visibleby Coomassie Blue staining (FIG. 14B, lanes a, b, e, and f).Reconstruction experiments demonstrated that the sensitivity ofimmunodetection with the α23K1 antiserum was less than one 23K6polypeptide per virion under the conditions for Western blot analysisdescribed herein.

The Ad2 proteinase of purified H2tsl virions was not detected in theWestern analysis illustrated by FIG. 14. However, as shown in FIG. 15,the proteinase was readily detected when more H2tsl virions were appliedto the gel. A similar difference between amounts of proteinases in Ad2and H2tsl virions was observed in virion radiolabeling experiments (FIG.17). Based on these results, it is estimated that H2tsl virions containapproximately 5-fold less proteinase than wild type virions. This amountis near the detection limit of the immunoblot assay (about 0.1 ngproteinase) unless gel lanes are overloaded with virus.

15. Immunospecificity of the α23K1 Antibody for the Ad2 Proteinass

FIGS. 14 and 15 testify to the immunospecificity of the α23K1 polyclonalantibody for Ad2 proteinase and its nonreactivity with other adenovirusor mammalian cell proteins. The anti-23K1 serum was made using agel-purified recombinant proteinase fusion protein, and care was takento insure that materials used for immunization were not contaminatedwith virion polypeptides. In FIG. 15, lanes e and f containing purifiedwild type and mutant Ad2 virion samples indicate no significant reactionof the α23K1 antibody with adenovirus proteins other than theapproximately 23 kDa proteinase. The weak immunoreaction observed withvirion component IIIa is due to other immunoreactive components in theserum, as shown by lanes a and b in the blot incubated with preimmuneserum. Lanes c, d, k, and l of the Western blot in FIG. 14B, which alsocontain Ad2 virion proteins, confirm this result. The FIG. 14 blot showsan additional weak immunoreaction with the adenovirus hexon protein. Thehexon band is a background band resulting from nonspecific reaction withthe antiserum: it results because the FIG. 14 blot was developed formaximum sensitivity, and also because the lot of alkalinephosphatase-conjugated anti-rabbit IgG used for this experiment gave arelatively high background. A comparison of the relative amounts of thehexon and proteinase proteins as indicated by Coomassie Blue stain (SA)contrasted with the relative intensity of immunoreaction with theantiserum (8B) further demonstrates the immunospecificity of the α23K1antibody for Ad2 proteinase and lack of significant immunoreactivitywith other adenovirus proteins.

In the Western blot of FIG. 14B, lanes g, h, i, and j, containingextracts from infected and uninfected HeLa cells, show no significantreaction of the α23K1 antibody with proteins other than theapproximately 23 kDa Ad2 proteinase band, in either the soluble orinsoluble fractions of uninfected and infected HeLa cell extracts. Thisindicates that the α23K1 antibody is also not significantlyimmunoreactive with mammalian cell proteins.

Furthermore, the 23K1 antiserum did not react with virion component VIIthat was separated from the proteinase polypeptide by chromatography onphosphocellulose in urea.

FIGS. 14 and 15 show that the α23K1 antiserum reacts strongly andspecifically to wild type and mutant (or variant) Ad2 proteinases frompurified virion, infected mammalian cell, and recombinant bacterial cellsources. The antibody is immunoreactive with active as well as inactiveAd2 proteinase, as shown by FIG. 15, lane h, containing the deletionvariant 23K11. In lanes containing HPLC-purified recombinant proteinases(lanes a, b, e, and f of FIG. 14 and lane h of FIG. 15), animmunoreactive upper band is seen. This upper band probably represents adifferently folded form of the recombinant Ad2 proteinase, since it isnot seen in the virion or infected cell lanes. The upper band protein ispresent in amounts not detectable by Coomassie Blue staining (FIG. 14A);however, the immunoreaction is strong. This indicates a specificreaction of the antibody to this upper band protein.

16. Detection of the Ad2 Proteinase in [³⁵ S]-Cysteine and ³³² PO₄-Labeled Virions

The Ad2 proteinase is expected to have eight cysteine residues, whilecomponent VII and its precursor have none. Ad2 and H2tsl virions werelabeled separately with [³⁵ S]-methionine, [³⁵ S]-cysteine, and ³² PO₄,and run on an SDS-polyacrylamide gel. Ad2 virions were labeled with [³⁵S]methionine or cysteine by incubating cells with the radioactive aminoacid in medium (Dulbecco's MEM) containing 5% of the normalconcentration of that amino acid as described by Anderson, (Virology,1990), usually from about 24 to 36 hr after infection.

FIG. 17 shows an autoradiogram of the gel. The film was exposed for 18days at -70° C. with an intensifying screen. Only the region of theautoradiogram between virion components pVI and VII is shown. Lanes aand b show Ad2 and H2tsl virions labeled with [³⁵ S]-methionine,respectively; lanes c and d show the two virions :labeled with [³⁵S]-cysteine; and lanes e and f show the virions labeled with ³² PO₄.HPLC-purified 23K6 (lane g) and 23KSa and b (lane h) were run as markersfor the Ad2 proteinase. The position of the Ad2 proteinase (arrow) wasdetermined from an immunoblot of a parallel gel probed with α23K1antiserum. Asterisks mark the positions of faintly [³² P]-labeledpolypeptides with mobilities similar to the Ad2 proteinase.

In FIG. 17, a distinct, [³⁵ S]-cysteine-labeled polypeptide was observedin wild type virions between the positions of pVII and VII (lane c).Significantly less [³⁵ S]-cysteine was present at this position in H2tslvirions (lane d) even though equal amounts of wild type and H2tslvirions were loaded on the gel. Confirmation that the cysteine-labeledpolypeptide is the proteinase was obtained by comparing a parallelimmunoblot with the autoradiogram. The [³⁵ S]-cysteine-labeled band andthe proteinase polypeptide had exactly the same mobility, and, in thisexperiment, both methods revealed the proteinase as a very closelyspaced doublet.

The Ad2 proteinase was previously reported to be phosphorylated(Chatterjee and Flint, Proc. Natl. Acad. Sci. USA 84:714-718 (1987)). InFIG. 17, a faint [³² P]-labeled component of wild type virions wasobserved having the mobility of the Ad2 proteinase (lane e). Thisevidence shows that, in contrast to the claim of Chatterjee and Flint(1987 supra), the adenovirus 2 proteinase polypeptide found inadenovirus virions is not phosphorylated to a significant extent. Afaintly labeled polypeptide with slightly higher mobility was observedin H2tsl virions (lane f). This [³² P]-labeled component did notcorrespond to a known Ad2 polypeptide, nor was a proteinase-relatedpolypeptide detected at this position by Western blot analysis. Analysisof virions labeled to high specific activity with [³⁵ S]-methionine(lanes a and b) showed that virion preparations contain numerousunidentified polypeptides or peptide fragments at low abundance.

The precursor to virion component VI, which is predicted to contain onecysteine residue near its carboxy-terminus, was well labeled with [³⁵S]-cysteine; however, no [³⁵ S]-cysteine was detected at the position ofcomponent VI in wild type virions (lanes c and d). Components pVI and VIwere readily observed with Coomassie Blue and stained with equalintensity. This result suggests that pVI may be processed at a secondsite near its carboxyterminus.

17. Location of the Proteinase in Virions

To locate the proteinase polypeptide in virions, pyridine-disrupted wildtype virions were fractionated into shell components and cores bysucrose gradient centrifugation as described (Prage et al., Virology42:341-358 (1970)). Each gradient fraction was analyzed for polypeptidecontent by SDS-polyacrylamide gel electrophoresis (FIG. 18A), and theproteinase was detected by immunoblot analysis of a parallel gel (FIG.18B). Specifically, purified wild type Ad2 virions (approximately 10¹²particles) were disrupted by incubation in 10% pyridine as described(Prage et al. (1970) supra), and virion cores were separated from outershell components by centrifugation through a 15-25% sucrose gradient at160,000×g for 165 minutes at 4° C. using a Beckman SW-41 rotor.Fractions of 1.5 ml were collected, concentrated, and analyzed onparallel SDS-polyacrylamide gels (lanes e-k). One gel was stained withCoomassie Blue (A). The proteins in the other gel wereelectrophoretically transferred to Immunobilon, which was then processedfor immunological detection of the proteinase using α23K1 serum (B).Also analyzed on each gel were Ad2 virions (lanes a, b, l, and m) andHPLC-purified 23K6 proteinase (lane c). Lane d (marked "B") is pelletedmaterial that was washed from the bottom of the centrifuge tube; lane kwas the top ("T") fraction of the gradient. The position of theproteinase is marked with arrows; the positions of other virion proteinsare shown at the right.

Although some proteinase was distributed throughout the gradient, themajority was found in fractions containing core proteins V and VII.

18. Number of Proteinase Polypeptides per Virion

The polypeptides from 2.5×10⁹, 10¹⁰, and 3×10¹⁰ wild type Ad2 virions(1.0 A₂₆₀ =1.1×10¹² virions, according to Maizel et al., Virology36:115-125 (1968)) were fractionated by SDS-polyacrylamide gelelectrophoresis along with two-fold increments of purified 23K10 and23K11 proteinases in amounts between 0.48 and 7.5 ng per lane. Theconcentrations of HPLC-purified 23K10 and 23K11 were determined bydensitometry of a second, Coomassie Blue-stained gel that was loadedwith 100 times as much recombinant polypeptide. The staining intensityof 23K10 and 23K11 was compared to 1.5 and 0.75 μg of soybean trypsininhibitor (SBTI) that was also fractionated on this gel. Theconcentration of the stock solution of SBTI was determined byquantitative amino acid analysis. Polypeptides from the first gel wereelectrophoretically transferred to Immobilon and Ad2 proteinase wasdetected with e23K1 serum. The proteinase band from 1×10¹⁰ virionsproduced the same staining intensity with anti-23K1 serum asapproximately 2 ng of 23K10 or approximately 5 ng of 23K11. Theseamounts correspond respectively to 5 and 13 molecules of proteinase pervirion.

19. Other Adenovirus Type Proteinases

The adenovirus proteinase amino acid sequences shown in FIG. 16 arepredicted from the proteinase coding sequences, which have beenpublished and are available from Genbank. References of the publishednucleotide sequences are listed below:

Human Ad2: Akusjarvi et al., Nucleic Acids Res. 9:1-17 (1981);

Human Ad3: Houde and Weber, Nucleic Acids Res. 16:11,374 (1988);

Human Ad4: Houde and Weber, Gene 54:51-56 (1987);

Human Ad5: Kruijer et al., Nucleic Acids Res. 8:6033-6042 (1980);

Human Ad12: Houde and Weber, Nucleic Acids Res. 16:7195 (1988);

Human Ad 40 and 41: Vos et al., Virology 163:1-10 (1988);

Bovine Ad3 (BAd3): Cai et al., Nucleic Acids Res. 18:5568 (1990); and

Bovine Ad4 (BAd4): Cai et al., Nucleic Acids Res. 18:5567 (1990).

20. Fractionation and sequence analysis of Ad12 Virion Components

This procedure for fractionating virus components was developed foridentifying the peptide cofactor required for Ad2 proteinase activity.Approximately 8×10¹² Ad12 virions suspended in 0.01M Tris-HCl, pH 8,0.001M EDTA, 10% pyridine were disrupted by incubating the suspension at0° C. for 30 min and then rapidly freezing and thawing the suspension.Virion components then were fractionated by size using a Centricon-10(Amicon, Inc.) filter unit. After an initial concentration bycentrifugation, the retentate was washed with 2 ml, then 0.5 ml ofwater, and then 1.0 ml and 0.5 ml of 1M ammonium bicarbonate. The waterwashes and initial filtrate were combined, concentrated to dryness byvacuum centrifugation, and then resuspended and dried several times fromwater. The bicarbonate extractions were similarly combined, dried, andwashed. The retentate was dissolved in SDS buffer and fractionated bySDS gel electrophoresis. Components VI and VII were obtainedindividually for protein sequence analysis after electrophoretictransfer of the proteins from an SDS-polyacrylamide gel to high capacityPVDF (Immobilon) sequencing membrane (Millipore, Cat. No. ISEQ26260) inCAPS buffer containing 0.05% SDS. The two filtrates (the pyridine andbicarbonate washes) were fractionated by reverse phase high performanceliquid chromatography (HPLC) on a 2.1×100 mm C₁₈ column (AquaporeOD-300, 7 micron) equilibrated in 0.1% trifluoroacetic acid (TFA) usinga Hewlett-Packard 1090 liquid chromatograph equipped with a diode arraydetector. The flow rate was 0.5 ml per min and peptides were eluted witha linear gradient of acetonitrile in 0.1% TFA.

Proteins and peptides were sequenced by automated Edman degradationusing an Applied Biosystems 470A sequencer equipped for on-linedetection of the phenylthiohydantoin-amino acid derivatives.

21. Ad12 virion-mediated cleavage of an artificial proteinase substrate

Artificial proteinase substrate was expressed upon induction of a pETexpression plasmid called pT7HEP1DBP (or pT7HIS2).

Plasmid pT7HEP1DBP (5346 bp) is a pET-3 derivative that expresses the231-amino acid T7 gene 2.5 protein (a single-stranded DNA bindingprotein) attached to a 17-amino acid leader sequence (FIG. 19). The249-amino acid HEP1DBP polypeptide serves as an artificial substrate forthe adenovirus EP; the leader peptide, MASMTGHHHHHHGMSGG- (SEQ ID NO:37), ends with the Ad2 proteinase recognition sequence -MSGG- (SEQ IDNO: 38) [Anderson, C. W., Virology, 177;259 (1990)], which is found atthe carboxy terminus of the amino-terminal cleavage fragment of virionprecursor pVI [Akusjarvi, G. and Persson, H., J. Virol., 38;469 (1981)][Sung, M. T. et al., J. Biol. Chem., 252;4981 (1977)]. The sixconsecutive histidine residues in the leader permit the product to bepurified by zinc-affinity chromatography [Hochuli, E. et al., J.Chromatogr, 411;177 (1987)] [Kagedal, L., Methods, and Applications(J-C. Janson and L. Ryden, Eds.), VCH Publishers, NY, 227 (1989)][Arnold, F. H. and Haymore, B. L., Science, 252;1796 (1991)]. pT7HEP1DBPwas constructed from elements of plasmid pT7AD23K13 and plasmid p3505;p3505 contains the T7 2.5 gene. First, the 595-bp segment of thepT7AD23K13 from the BstEII site to the ECPRI site was copied using PCRand oligonucleotide primers 5'-CCTACATATGGCTTCTATGACTGGTCACCACCA-3'(sense strand) (SEQ ID NO: 35) and 5'-GGCCCTTTCGTCTTCAAG-3' (SEQ ID NO:34). The latter oligonucleotide corresponds to anti-sense sequence justcounterclockwise (toward the bla gene) of the EcoRI site in pET-3. Theaminoterminal sense strand primer provided an NdeI site with amethionine initiation codon followed by a sequence that encodes thefirst 6 amino acids of the leader and then a sequence homologous topT7AD23K13 from the BstEII site at the beginning of the oligohistidinetrack. After cleavage with NdeI and EcoRI, the amplified fragment wasligated with similarly cut pT7AD23K13 to make the intermediate plasmidpT7Hisl. Next, the T7 gene 2.5 segment was copied from plasmid p3505using the amino-terminal sense strand primer5'-CCCGGTCACCACCACCATCACCATGGTATGAGCGGCGGCATGGCTAAGAAGAT-3'(SEQ ID NO:36), (the BstEII recognition sequence and homology to gene 2.5 areunderlined) (SEQ ID NO: 36 and the EcoRI site primer,5'-GGCCCTTTCGTCTTCAAG-3' (SEQ ID NO: 23). After cleavage with BstEII andEcoRI, the amplified fragment was ligated with similarly cleaved pT7HIS1DNA to produce pT7HEP1DBP (FIG. 19).

[³⁵ S]Methionine-labeled HEP1DBP substrate was incubated with 1×10¹¹disrupted Ad12 virions alone, or with Ad12 virions and ˜5 μg purifiedrecombinant Ad2 EP polypeptide. Samples were removed after 0, 30, and120 min incubation at 50° and fractionated by SDS-polyacrylamide gelelectrophoresis. An autoradiogram was made from the dried gel.

Equivalents

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments of the invention described herein. Such equivalents areintended to be encompassed by the claims.

                                      TABLE 2                                     __________________________________________________________________________    Adenovirus Proteinase Expression Plasmids and Products                        Plasmid.sup.a /                                                                      Parent  Protein                                                                           Size.sup.b                                                                             Amino-Terminal Sequence.sup.c/                                                                            Activity/             Vector Plasmid Name                                                                              kDa aa   Protein Structure           Conditions            __________________________________________________________________________    pT7AD23K1                                                                            pCA93a  23K1                                                                              25  220  ASMTGGQQMGRDPAAAMGSSEQELKAIVKD-                                                                           Active                pET-1a                      T7 gene 10 (12) + linker (4)                                                                              Uninduced,                                        Ad2 PTNase (204)            stationary                                                                    phase                 pT7AD23K2                                                                            pT7AD23K1                                                                             23K2a                                                                             26  231  MRAKLLGIVLTTPIAISSFASTDPAAANGSSEQE-                                                                       Active                pET-12b                     OmpT (23) + linker (4) +    Uninduced,                                        Ad2 PTNase (204)            stationary                                                                    phase                                23K2b                                                                             24  211  STDPAAAMGSSEQELKAIVKDLGCGPYFLGTYDK-                                           OmpT (3) + linker (4) +                                                       Ad2 PTNase (204)                                  pT7AD23K5                                                                            pT7AD23K2                                                                             23K5a                                                                             26  227  MRAKLLGIVLTTPIAISSFASTHMGSSEQE-                                                                           Active                pET-12b                     OmpT (22) + linker (1) +    Uninduced,                                        Ad2 PTNase (204)            stationary                                                                    phase                                23K5b                                                                             23  207  STHMGSSEQELKAIVKDLGCGPYFLGTYDKRFP-                                            OmpT (2) + linker (1) +                                                       Ad2 PTNase (204)                                  pT7AD23K6                                                                            pT7AD23K5                                                                             23K6                                                                              23  204/203                                                                            (M)GSSEQELKAIVKDLGCGPYFLGTYDKRFP-                                                                         Active                                            Ad2 PTNase                  Induced,                                                                      log phase             pT7AD23K8                                                                            pT7AD23K6                                                                             23K8                                                                              23  204/203                                                                            (M)GSSEQELKAIVKDLGCGPYFLGTYDKRFP-                                                                         Active                pET-3c                      Ad2 PNTase with AflII site  Induced,                                                                      log phase             pT7AD23K10                                                                           pT7AD23K6                                                                             23K10                                                                             23  204/203                                                                            (M)GSSEQELKAIVKDLGCGPYFLGTYDKRFPG-                                                                        Active                pET-3C                      Ad2 PTNase                  Induced,                                                                      log phase             pT7AD23K11                                                                           pT7AD23K6                                                                             23K11                                                                             22  194  GSSDLGCGPYFLGTYDKRFPGFVSPHKLACAIV-                                                                        Inactive              pET-12b                     Ad2 PTNase variant (E.sub.5 QELKAIVK.sub.13                                   deleted)                                          pT7AD23K13                                                                           pT7AD23K8                                                                             23K13                                                                             24  213/212                                                                            (M)GSSEQELKAIVKDLGCGPYFLGTYDKRFPG-                                                                        Active                pET-3c                      Ad2 PNTase variant (GHHHHHHNM                                                                             Induced,                                          at carboxy-terminus)        log phase             pT7AD23K15                                                                           pT7AD23K5                                                                             23K15a                                                                            26  229  MRAKLLGIVLTTPIAISSFASTHMGSEQE-                                                                            Not                   pET-12b                     OmpT (22) + linker (1) +    determined                                        Ad12 PTNase (206)                                                23K15b                                                                            24  209  STHMGSSEQELKAIVKDLGCGPYFLGTYDKRFP-                                            OmpT (2) + linker (1) +                                                       Ad12 PTNase (206)                                 pT7AD23K16                                                                           pT7AD23K15                                                                            23K16                                                                             23  206/205                                                                            (M)GSSEQELTAIVRDLGCGPYFLGTFDKRFPG-                                                                        Active                pET-12b                     Ad12 PTNase                 Induced,                                                                      log phase             pT7AD23K18                                                                           pT7AD23K8                                                                             H2ts1                                                                             23  204/203                                                                            (M)GS SEQELKAIVKDLGCGPYFLGTYDKRFP-                                                                        Temperature-          pET-3c                      ts Ad2 PNTase with AflII site;                                                                            Sensitive                                         P to L mutation in codon 137                      __________________________________________________________________________     .sup.a The Ad2 proteinase expression plasmids contain the Ad2 genome          segment between nucleotide 21,778 at the initiation codon in the L3 23 kD     reading frame and 22,667 at the EcoRV site in the DBP gene. pCA93a,           pT7AD23K1, and pT7AD23K2 also have the short sequence between the Ad2         PvuII site at 21,770 and the proteinase initiation codon. The Ad12            proteinase expression plasmids contain nucleotides 127 to 809 of the          published sequence of the Ad12 proteinase (Houde and Weber, Nucleic Acids     Res. 16:1795 (1988)).                                                         .sup.b Predicted molecular weight for the expected polypeptide products o     the plasmids. aa = amino acids.                                               .sup.c/ The predicted aminoterminal sequences of approximately 30 amino       acids is given; residues confirmed by sequence analysis are underlined.       Gaps in the confirmed sequence indicate a technical problem in                identification of the PTH aminoacid derivative and do not imply that the      sequence obtained differed from the predicted sequence. Removal of the        aminoterminal methionine was incomplete for 23K6, 23K8, 23K10, 23K11,         23K13, and 23K16. The predicted protein structure is given; the number of     amino acids derived from each part is indicated in (). PTNase =               proteinase.                                                              

                  TABLE 3                                                         ______________________________________                                        Activation of Ad2 proteinase activity by negatively                           charged polymers                                                              Effector*       Rate † (pmol                                                                        Stimulation ‡                         (concentration) substrate min.sup.-1)                                                                      (fold)                                           ______________________________________                                        None            2.8          1.0                                              Double-stranded DNA                                                           Linear                                                                        Ad2 (5.9 pM)    25.6         9.3                                              T7 (2.5 pM)     26.1         9.5                                              Circular                                                                      SV40 (27.9 pM)  24.4         8.9                                              φX174 RF (18 pM)                                                                          23.3         8.5                                              Single-stranded DNA                                                           Linear                                                                        M13 (+strand) (61 pM)                                                                         27.0         9.8                                              Circular                                                                      φX174 (+strand) (107 pM)                                                                  26.5         9.6                                              Four deoxyribonucleoside                                                                      2.6          <1.0                                             monophosphates (112 nM)                                                       RNA                                                                           Yeast tRNA (10.2 nM)                                                                          19.8         7.2                                              Protein                                                                       Polyglutamic acid (2.4 nM)                                                                    24.5         8.9                                              Polyaspartic acid (12 nM)                                                                     13.7         5.0                                              Polylysine (33 nM)                                                                            <10.0        <1.0                                             Amino acids                                                                   Glutamic acid (780 nM)                                                                        2.3          <1.0                                             Aspartic acid (1.38 μM)                                                                    2.1          <1.0                                                             12.9         4.7                                              Heparin (33 nM) 12.9         4.7                                              ______________________________________                                         *The concentrations of effectors in units of moles of molecules per litre     that gave maximal stimulation of proteinase activity.                         † All assays contained 8.3 nM rEP protein, 98 nM pVIc peptide, and     1 μM (LeuArg-Gly-Gly-NH).sub.2rhodamine. The rate of substrate             hydrolysis by the rEP protein alone was less than 0.014 pmol substrate        min.sup.-1 ; in presence of 5.9 pmol Ad2 DNA, the rate of hydrolysis was      0.135 pmol substrate min.sup.-1.                                              ‡ The rate of hydrolysis of substrate in the presence of           effector divided by the rate in its absence.                             

    __________________________________________________________________________    SEQUENCE LISTING                                                              (1) GENERAL INFORMATION:                                                      (iii) NUMBER OF SEQUENCES: 45                                                 (2) INFORMATION FOR SEQ ID NO:1:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 612 base pairs                                                    (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: double                                                      (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: DNA (genomic)                                             (ix) FEATURE:                                                                 (A) NAME/KEY: CDS                                                             (B) LOCATION: 1..612                                                          (D) OTHER INFORMATION: /product="Ad2 proteinase"                              (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:                                       ATGGGCTCCAGTGAGCAGGAACTGAAAGCCATTGTCAAAGATCTTGGT48                            MetGlySerSerGluGlnGluLeuLysAlaIleValLysAspLeuGly                              151015                                                                        TGTGGGCCATATTTTTTGGGCACCTATGACAAGCGCTTTCCAGGCTTT96                            CysGlyProTyrPheLeuGlyThrTyrAspLysArgPheProGlyPhe                              202530                                                                        GTTTCTCCACACAAGCTCGCCTGCGCCATAGTCAATACGGCCGGTCGC144                           ValSerProHisLysLeuAlaCysAlaIleValAsnThrAlaGlyArg                              354045                                                                        GAGACTGGGGGCGTACACTGGATGGCCTTTGCCTGGAACCCGCGCTCA192                           GluThrGlyGlyValHisTrpMetAlaPheAlaTrpAsnProArgSer                              505560                                                                        AAAACATGCTACCTCTTTGAGCCCTTTGGCTTTTCTGACCAACGACTC240                           LysThrCysTyrLeuPheGluProPheGlyPheSerAspGlnArgLeu                              65707580                                                                      AAGCAGGTTTACCAGTTTGAGTACGAGTCACTCCTGCGCCGTAGCGCC288                           LysGlnValTyrGlnPheGluTyrGluSerLeuLeuArgArgSerAla                              859095                                                                        ATTGCTTCTTCCCCCGACCGCTGTATAACGCTGGAAAAGTCCACCCAA336                           IleAlaSerSerProAspArgCysIleThrLeuGluLysSerThrGln                              100105110                                                                     AGCGTGCAGGGGCCCAACTCGGCCGCCTGTGGACTATTCTGCTGCATG384                           SerValGlnGlyProAsnSerAlaAlaCysGlyLeuPheCysCysMet                              115120125                                                                     TTTCTCCACGCCTTTGCCAACTGGCCCCAAACTCCCATGGATCACAAC432                           PheLeuHisAlaPheAlaAsnTrpProGlnThrProMetAspHisAsn                              130135140                                                                     CCCACCATGAACCTTATTACCGGGGTACCCAACTCCATGCTTAACAGT480                           ProThrMetAsnLeuIleThrGlyValProAsnSerMetLeuAsnSer                              145150155160                                                                  CCCCAGGTACAGCCCACCCTGCGTCGCAACCAGGAACAGCTCTACAGC528                           ProGlnValGlnProThrLeuArgArgAsnGlnGluGlnLeuTyrSer                              165170175                                                                     TTCCTGGAGCGCCACTCGCCCTACTTCCGCAGCCACAGTGCGCAGATT576                           PheLeuGluArgHisSerProTyrPheArgSerHisSerAlaGlnIle                              180185190                                                                     AGGAGCGCCACTTCTTTTTGTCACTTGAAAAACATG612                                       ArgSerAlaThrSerPheCysHisLeuLysAsnMet                                          195200                                                                        (2) INFORMATION FOR SEQ ID NO:2:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 204 amino acids                                                   (B) TYPE: amino acid                                                          (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: protein                                                   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:                                       MetGlySerSerGluGlnGluLeuLysAlaIleValLysAspLeuGly                              151015                                                                        CysGlyProTyrPheLeuGlyThrTyrAspLysArgPheProGlyPhe                              202530                                                                        ValSerProHisLysLeuAlaCysAlaIleValAsnThrAlaGlyArg                              354045                                                                        GluThrGlyGlyValHisTrpMetAlaPheAlaTrpAsnProArgSer                              505560                                                                        LysThrCysTyrLeuPheGluProPheGlyPheSerAspGlnArgLeu                              65707580                                                                      LysGlnValTyrGlnPheGluTyrGluSerLeuLeuArgArgSerAla                              859095                                                                        IleAlaSerSerProAspArgCysIleThrLeuGluLysSerThrGln                              100105110                                                                     SerValGlnGlyProAsnSerAlaAlaCysGlyLeuPheCysCysMet                              115120125                                                                     PheLeuHisAlaPheAlaAsnTrpProGlnThrProMetAspHisAsn                              130135140                                                                     ProThrMetAsnLeuIleThrGlyValProAsnSerMetLeuAsnSer                              145150155160                                                                  ProGlnValGlnProThrLeuArgArgAsnGlnGluGlnLeuTyrSer                              165170175                                                                     PheLeuGluArgHisSerProTyrPheArgSerHisSerAlaGlnIle                              180185190                                                                     ArgSerAlaThrSerPheCysHisLeuLysAsnMet                                          195200                                                                        (2) INFORMATION FOR SEQ ID NO:3:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 90 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: double                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:                                       ATACATATGCGGGCGAAACTCCTAGGAATAGTCCTGACAACCCCTATCGCGATCAGCTCT60                TTTGCGTCGACCCATATGGGCTCCAGTGAG90                                              (2) INFORMATION FOR SEQ ID NO:4:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 9 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:                                       GlyHisHisHisHisHisHisAsnMet                                                   15                                                                            (2) INFORMATION FOR SEQ ID NO:5:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 618 base pairs                                                    (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: double                                                      (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: DNA (genomic)                                             (ix) FEATURE:                                                                 (A) NAME/KEY: CDS                                                             (B) LOCATION: 1..618                                                          (D) OTHER INFORMATION: /product="Ad12 proteinase"                             (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:                                       ATGGGTTCAAGCGAACAGGAGCTGACGGCGATTGTTCGAGATCTAGGC48                            MetGlySerSerGluGlnGluLeuThrAlaIleValArgAspLeuGly                              151015                                                                        TGTGGGCCCTATTTTTTGGGCACCTTTGACAAACGTTTTCCGGGTTTT96                            CysGlyProTyrPheLeuGlyThrPheAspLysArgPheProGlyPhe                              202530                                                                        GTGTCTCGCGACCGCTTATCATGCGCTATTGTTAACACTGCCGGTCGT144                           ValSerArgAspArgLeuSerCysAlaIleValAsnThrAlaGlyArg                              354045                                                                        GAAACTGGGGGCGTACACTGGCTGGCCTTTGGATGGAACCCCAAATCG192                           GluThrGlyGlyValHisTrpLeuAlaPheGlyTrpAsnProLysSer                              505560                                                                        CACACTTGCTATTTATTCGATCCATTTGGATTTTCTGATCAGCGACTG240                           HisThrCysTyrLeuPheAspProPheGlyPheSerAspGlnArgLeu                              65707580                                                                      AAACAAATCTATCAGTTTGAGTACGAAAGTCTGTTGCGCCGTAGTGCG288                           LysGlnIleTyrGlnPheGluTyrGluSerLeuLeuArgArgSerAla                              859095                                                                        CTAGCGGCCACTAAAGACCGATGCGTCACCCTAGAAAAGTCAACCCAA336                           LeuAlaAlaThrLysAspArgCysValThrLeuGluLysSerThrGln                              100105110                                                                     ACTGTACAAGGACCGTTTTCTGCAGCGTGCGGCCTGTTTTGTTGTATG384                           ThrValGlnGlyProPheSerAlaAlaCysGlyLeuPheCysCysMet                              115120125                                                                     TTCTTACATGCTTTTACTCACTGGCCTGACCATCCAATGGATAAAAAT432                           PheLeuHisAlaPheThrHisTrpProAspHisProMetAspLysAsn                              130135140                                                                     CCCACTATGGACCTACTTACTGGGGTGCCTAATTGTATGCTACAAAGT480                           ProThrMetAspLeuLeuThrGlyValProAsnCysMetLeuGlnSer                              145150155160                                                                  CCTCAGGTAGTGGGCACACTTCAACGCAATCAGAATGAATTGTATAAA528                           ProGlnValValGlyThrLeuGlnArgAsnGlnAsnGluLeuTyrLys                              165170175                                                                     TTCTTAAACAGTCTGTCCCCTTACTTTCGTCACAACCGCGAGCGCATA576                           PheLeuAsnSerLeuSerProTyrPheArgHisAsnArgGluArgIle                              180185190                                                                     GAAAAAGCTACATCTTTTACTAAAATGCAAAATGGACTCAAA618                                 GluLysAlaThrSerPheThrLysMetGlnAsnGlyLeuLys                                    195200205                                                                     (2) INFORMATION FOR SEQ ID NO:6:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 206 amino acids                                                   (B) TYPE: amino acid                                                          (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: protein                                                   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:                                       MetGlySerSerGluGlnGluLeuThrAlaIleValArgAspLeuGly                              151015                                                                        CysGlyProTyrPheLeuGlyThrPheAspLysArgPheProGlyPhe                              202530                                                                        ValSerArgAspArgLeuSerCysAlaIleValAsnThrAlaGlyArg                              354045                                                                        GluThrGlyGlyValHisTrpLeuAlaPheGlyTrpAsnProLysSer                              505560                                                                        HisThrCysTyrLeuPheAspProPheGlyPheSerAspGlnArgLeu                              65707580                                                                      LysGlnIleTyrGlnPheGluTyrGluSerLeuLeuArgArgSerAla                              859095                                                                        LeuAlaAlaThrLysAspArgCysValThrLeuGluLysSerThrGln                              100105110                                                                     ThrValGlnGlyProPheSerAlaAlaCysGlyLeuPheCysCysMet                              115120125                                                                     PheLeuHisAlaPheThrHisTrpProAspHisProMetAspLysAsn                              130135140                                                                     ProThrMetAspLeuLeuThrGlyValProAsnCysMetLeuGlnSer                              145150155160                                                                  ProGlnValValGlyThrLeuGlnArgAsnGlnAsnGluLeuTyrLys                              165170175                                                                     PheLeuAsnSerLeuSerProTyrPheArgHisAsnArgGluArgIle                              180185190                                                                     GluLysAlaThrSerPheThrLysMetGlnAsnGlyLeuLys                                    195200205                                                                     (2) INFORMATION FOR SEQ ID NO:7:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 30 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (v) FRAGMENT TYPE: N-terminal                                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:                                       AlaSerMetThrGlyGlyGlnGlnMetGlyArgAspProAlaAlaAla                              151015                                                                        MetGlySerSerGluGlnGluLeuLysAlaIleValLysAsp                                    202530                                                                        (2) INFORMATION FOR SEQ ID NO:8:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 34 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (v) FRAGMENT TYPE: N-terminal                                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:                                       MetArgAlaLysLeuLeuGlyIleValLeuThrThrProIleAlaIle                              151015                                                                        SerSerPheAlaSerThrAspProAlaAlaAlaMetGlySerSerGlu                              202530                                                                        GlnGlu                                                                        (2) INFORMATION FOR SEQ ID NO:9:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 34 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (v) FRAGMENT TYPE: N-terminal                                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:                                       SerThrAspProAlaAlaAlaMetGlySerSerGluGlnGluLeuLys                              151015                                                                        AlaIleValLysAspLeuGlyCysGlyProTyrPheLeuGlyThrTyr                              202530                                                                        AspLys                                                                        (2) INFORMATION FOR SEQ ID NO:10:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 30 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (v) FRAGMENT TYPE: N-terminal                                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10:                                      MetArgAlaLysLeuLeuGlyIleValLeuThrThrProIleAlaIle                              151015                                                                        SerSerPheAlaSerThrHisMetGlySerSerGluGlnGlu                                    202530                                                                        (2) INFORMATION FOR SEQ ID NO:11:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 33 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (v) FRAGMENT TYPE: N-terminal                                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11:                                      SerThrHisMetGlySerSerGluGlnGluLeuLysAlaIleValLys                              151015                                                                        AspLeuGlyCysGlyProTyrPheLeuGlyThrTyrAspLysArgPhe                              202530                                                                        Pro                                                                           (2) INFORMATION FOR SEQ ID NO:12:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 33 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (v) FRAGMENT TYPE: N-terminal                                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12:                                      GlySerSerAspLeuGlyCysGlyProTyrPheLeuGlyThrTyrAsp                              151015                                                                        LysArgPheProGlyPheValSerProHisLysLeuAlaCysAlaIle                              202530                                                                        Val                                                                           (2) INFORMATION FOR SEQ ID NO:13:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 29 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (v) FRAGMENT TYPE: N-terminal                                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:13:                                      MetArgAlaLysLeuLeuGlyIleValLeuThrThrProIleAlaIle                              151015                                                                        SerSerPheAlaSerThrHisMetGlySerGluGlnGlu                                       2025                                                                          (2) INFORMATION FOR SEQ ID NO:14:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 33 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (v) FRAGMENT TYPE: N-terminal                                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:14:                                      SerThrHisMetGlySerSerGluGlnGluLeuLysAlaIleValLys                              151015                                                                        AspLeuGlyCysGlyProTyrPheLeuGlyThrTyrAspLysArgPhe                              202530                                                                        Pro                                                                           (2) INFORMATION FOR SEQ ID NO:15:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 250 amino acids                                                   (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:15:                                      MetGluAspIleAsnPheAlaSerLeuAlaProArgHisGlySerArg                              151015                                                                        ProPheMetGlyAsnTrpGlnAspIleGlyThrSerAsnMetSerGly                              202530                                                                        GlyAlaPheSerTrpGlySerLeuTrpSerGlyIleLysAsnPheGly                              354045                                                                        SerThrIleLysAsnTyrGlySerLysAlaTrpAsnSerSerThrGly                              505560                                                                        GlnMetLeuArgAspLysLeuLysGluGlnAsnPheGlnGlnLysVal                              65707580                                                                      ValAspGlyLeuAlaSerGlyIleSerGlyValValAspLeuAlaAsn                              859095                                                                        GlnAlaValGlnAsnLysIleAsnSerLysLeuAspProArgProPro                              100105110                                                                     ValGluGluProProProAlaValGluThrValSerProGluGlyArg                              115120125                                                                     GlyGluLysArgProArgProAspArgGluGluThrLeuValThrGln                              130135140                                                                     IleAspGluProProSerTyrGluGluAlaLeuLysGlnGlyLeuPro                              145150155160                                                                  ThrThrArgProIleAlaProMetAlaThrGlyValLeuGlyGlnHis                              165170175                                                                     ThrProValThrLeuAspLeuProProProAlaAspThrGlnGlnLys                              180185190                                                                     ProValLeuProGlyProSerAlaValValValThrArgProSerArg                              195200205                                                                     AlaSerLeuArgArgAlaAlaSerGlyProArgSerMetArgProVal                              210215220                                                                     AlaSerGlyAsnTrpGlnSerThrLeuAsnSerIleValGlyLeuGly                              225230235240                                                                  ValGlnSerLeuLysArgArgArgCysPhe                                                245250                                                                        (2) INFORMATION FOR SEQ ID NO:16:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 214 amino acids                                                   (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:16:                                      MetGlySerSerGluGlnGluLeuValAlaIleAlaArgAspLeuGly                              151015                                                                        CysGlySerTyrPheLeuGlyThrPheAspLysArgPheProGlyPhe                              202530                                                                        MetAlaProAsnLysLeuAlaCysAlaIleValAsnThrAlaGlyArg                              354045                                                                        GluThrGlyGlyValHisTrpLeuAlaLeuAlaTrpAsnProLysSer                              505560                                                                        HisThrCysTyrLeuPheAspProPheGlyPheSerAspGluArgLeu                              65707580                                                                      LysGlnIleTyrGlnPheGluTyrGluGlyLeuLeuLysArgSerAla                              859095                                                                        LeuAlaSerThrProAspHisCysIleThrLeuValLysSerThrGln                              100105110                                                                     ThrValGlnGlyProPheSerAlaAlaCysGlyLeuPheCysCysMet                              115120125                                                                     PheLeuHisAlaPheIleHisTrpProSerAsnProMetGluGlnAsn                              130135140                                                                     ProThrMetAspLeuLeuThrGlyValProAsnSerMetLeuGlnSer                              145150155160                                                                  ProGlnValGluProThrLeuArgArgAsnGlnGluArgLeuTyrArg                              165170175                                                                     PheLeuThrGlnHisSerProTyrPheArgArgHisArgGluArgIle                              180185190                                                                     GluLysAlaThrAlaPheAspGlnMetLysAsnAlaGlnValLeuPhe                              195200205                                                                     HisAsnLysIlePheTyr                                                            210                                                                           (2) INFORMATION FOR SEQ ID NO:17:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 205 amino acids                                                   (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:17:                                      MetGlySerSerGluGlnGluLeuValAlaIleValArgGluLeuGly                              151015                                                                        CysGlyProTyrPheLeuGlyThrPheAspLysArgPheProGlyPhe                              202530                                                                        MetAlaProHisLysLeuAlaCysAlaIleValAsnThrAlaGlyArg                              354045                                                                        GluThrGlyGlyValHisTrpLeuAlaLeuAlaTrpAsnProLysAsn                              505560                                                                        ArgThrCysTyrLeuPheAspProPheGlyPheSerAspGluArgLeu                              65707580                                                                      LysGlnIleTyrGlnPheGluTyrGluGlyLeuLeuLysArgSerAla                              859095                                                                        LeuAlaSerThrProAspHisCysIleThrLeuIleLysSerThrGln                              100105110                                                                     ThrValGlnGlyProPheSerAlaAlaCysGlyLeuPheCysCysMet                              115120125                                                                     PheLeuHisAlaPheValAsnTrpProThrSerProMetGluArgAsn                              130135140                                                                     ProThrMetAspLeuLeuThrGlyValProAsnSerMetLeuGlnSer                              145150155160                                                                  ProGlnValValProThrLeuArgHisAsnGlnGluArgLeuTyrArg                              165170175                                                                     PheLeuAlaGlnArgSerProTyrPheGlnArgHisCysGluArgIle                              180185190                                                                     LysLysAlaThrAlaPheAspGlnMetLysAsnAsnMet                                       195200205                                                                     (2) INFORMATION FOR SEQ ID NO:18:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 209 amino acids                                                   (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:18:                                      MetThrCysGlySerGlyAsnGlySerSerGluGlnGluLeuLysAla                              151015                                                                        IleValArgAspLeuGlyCysGlyProTyrPheLeuGlyThrPheAsp                              202530                                                                        LysArgPheProGlyPheMetAlaProAspLysLeuAlaCysAlaIle                              354045                                                                        ValAsnThrAlaGlyArgGluThrGlyGlyGluHisTrpLeuAlaPhe                              505560                                                                        GlyTrpAsnProArgTyrAsnThrCysTyrLeuPheAspProPheGly                              65707580                                                                      PheSerAspGluArgLeuLysGlnIleTyrGlnPheGluTyrGluGly                              859095                                                                        LeuLeuArgArgSerAlaLeuAlaThrLysAspArgCysIleThrLeu                              100105110                                                                     GluLysSerThrGlnSerValGlnGlyProArgSerAlaAlaCysGly                              115120125                                                                     LeuPheCysCysMetPheLeuHisAlaPheValHisTrpProAspArg                              130135140                                                                     ProMetAspGlyAsnProThrMetLysLeuValThrGlyValSerAsn                              145150155160                                                                  SerMetLeuGlnSerProGlnValGlnProThrLeuArgArgAsnGln                              165170175                                                                     GluValLeuTyrArgPheLeuAsnThrHisSerSerTyrPheArgSer                              180185190                                                                     HisArgAlaArgIleGluArgAlaThrAlaPheAspArgMetAspMet                              195200205                                                                     Gln                                                                           (2) INFORMATION FOR SEQ ID NO:19:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 201 amino acids                                                   (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:19:                                      MetAlaAlaGlySerGlyGluGlnGluLeuArgAlaIleIleArgAsp                              151015                                                                        LeuGlyCysGlyProTyrPheLeuGlyThrPheAspLysArgPhePro                              202530                                                                        GlyPheMetAlaProHisLysValAlaCysAlaIleValAsnThrAla                              354045                                                                        GlyArgGluThrGlyGlyGluHisTrpLeuAlaPheAlaTrpAsnPro                              505560                                                                        ArgSerAsnThrCysTyrLeuPheAspProPheGlyPheSerAspGln                              65707580                                                                      ArgLeuLysGlnIleTyrGlnPheGluTyrGluGlyLeuLeuArgArg                              859095                                                                        SerAlaLeuAlaThrLysAspArgCysValThrTrpLysSerHisGln                              100105110                                                                     ThrCysArgValArgValGlyArgCysGlyPheSerAlaAlaCysSer                              115120125                                                                     ThrAlaCysAlaTrpProThrProMetAspLysAsnProThrMetAsn                              130135140                                                                     LeuLeuThrGlyValProAsnGlyMetLeuGlnSerProGlnValGlu                              145150155160                                                                  ProThrLeuArgArgAsnGlnGluAlaLeuTyrArgPheLeuAsnSer                              165170175                                                                     HisSerAlaTyrPheArgSerHisArgAlaArgIleGluLysAlaThr                              180185190                                                                     AlaPheAspArgMetAsnGlnAspMet                                                   195200                                                                        (2) INFORMATION FOR SEQ ID NO:20:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 204 amino acids                                                   (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:20:                                      MetGlySerArgGluGluGluLeuArgPheIleLeuHisAspLeuGly                              151015                                                                        ValGlyProTyrPheLeuGlyThrPheAspLysHisPheProGlyPhe                              202530                                                                        IleSerLysAspArgMetSerCysAlaIleValAsnThrAlaGlyArg                              354045                                                                        GluThrGlyGlyValHisTrpLeuAlaMetAlaTrpHisProAlaSer                              505560                                                                        GlnThrPheTyrMetPheAspProPheGlyPheSerAspGlnLysLeu                              65707580                                                                      LysGlnIleTyrAsnPheGluTyrGlnGlyLeuLeuLysArgSerAla                              859095                                                                        LeuThrSerThrAlaAspArgCysLeuThrLeuIleGlnSerThrGln                              100105110                                                                     SerValGlnGlyProAsnSerAlaAlaCysGlyLeuPheCysCysMet                              115120125                                                                     PheLeuHisAlaPheValArgTrpProLeuArgAlaMetAspAsnAsn                              130135140                                                                     ProThrMetAsnLeuIleHisGlyValProAsnAsnMetLeuGluSer                              145150155160                                                                  ProSerSerGlnAsnValPheLeuArgAsnGlnGlnAsnLeuTyrArg                              165170175                                                                     PheLeuArgArgHisSerProHisPheValLysHisAlaAlaGlnIle                              180185190                                                                     GluAlaAspThrAlaPheAspLysMetLeuThrAsn                                          195200                                                                        (2) INFORMATION FOR SEQ ID NO:21:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 202 amino acids                                                   (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:21:                                      MetSerGlyLeuSerGluLysGluValPheLeuLeuLeuSerSerLeu                              151015                                                                        GlnCysThrHisGlyPheLeuGlyThrPheAspCysArgPheProGly                              202530                                                                        PheIleAsnLysValLysValGlnThrAlaIleIleAsnThrGlyPro                              354045                                                                        ArgGluGlnGlyGlyIleHisTrpIleAlaLeuAlaTrpAspProLys                              505560                                                                        SerTyrGlnMetPheIlePheAspProLeuGlyTrpLysAsnAspGln                              65707580                                                                      LeuMetLysTyrTyrLysPheSerTyrSerAsnLeuIleLysArgSer                              859095                                                                        AlaLeuSerSerProAspLysCysValLysValIleLysAsnSerGln                              100105110                                                                     SerValGlnCysThrCysAlaGlySerCysGlyLeuPheCysValPhe                              115120125                                                                     PheLeuTyrCysPheTyrLysTyrLysSerAsnAlaPheLysAsnCys                              130135140                                                                     LeuPheGlnSerLeuTyrGlySerIleProSerLeuThrProProAsn                              145150155160                                                                  ProThrAsnLeuHisLysAsnGlnAspPheLeuTyrLysPhePheLys                              165170175                                                                     GluLysSerLeuTyrPheArgGlnAsnGluGluTyrIleValSerAsn                              180185190                                                                     ThrLysIleGlyLeuIleLysSerHisIle                                                195200                                                                        (2) INFORMATION FOR SEQ ID NO:22:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 24 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:22:                                      CCCGTCGACCCATATGGGCTCCAG24                                                    (2) INFORMATION FOR SEQ ID NO:23:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 18 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (iv) ANTI-SENSE: YES                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:23:                                      GGCCCTTTCGTCTTCAAG18                                                          (2) INFORMATION FOR SEQ ID NO:24:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 35 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:24:                                      CCCCATATGGGCTCCTCAGATCTTGGTTGTGGGCC35                                         (2) INFORMATION FOR SEQ ID NO:25:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 23 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:25:                                      TAATACGACTCACTATAGGGAGA23                                                     (2) INFORMATION FOR SEQ ID NO:26:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 38 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (iv) ANTI-SENSE: YES                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:26:                                      CTTGGATCCATTATTTTTACATGTTCTTAAGGTGACAA38                                      (2) INFORMATION FOR SEQ ID NO:27:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 49 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:27:                                      TTAAGAACATGGGTCACCACCACCATCACCATAACATGTAAAAATAATG49                           (2) INFORMATION FOR SEQ ID NO:28:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 49 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (iv) ANTI-SENSE: YES                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:28:                                      GATCCATTATTTTTACATGTTATGGTGATGGTGGTGGTGACCCATGTTC49                           (2) INFORMATION FOR SEQ ID NO:29:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 25 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:29:                                      CCCGTCGACCCATATGGGTTCAAGC25                                                   (2) INFORMATION FOR SEQ ID NO:30:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 20 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (iv) ANTI-SENSE: YES                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:30:                                      CCCAAGCTTGTACTCCAATG20                                                        (2) INFORMATION FOR SEQ ID NO:31:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 13 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (v) FRAGMENT TYPE: N-terminal                                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:31:                                      AlaLysLysArgSerAspGlnHisProValArgValArg                                       1510                                                                          (2) INFORMATION FOR SEQ ID NO:32:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 249 amino acids                                                   (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:32:                                      MetAlaSerMetThrGlyHisHisHisHisHisHisGlyMetSerGly                              151015                                                                        GlyMetAlaLysLysIlePheThrSerAlaLeuGlyThrAlaGluPro                              202530                                                                        TyrAlaTyrIleAlaLysProAspTyrGlyAsnGluGluArgGlyPhe                              354045                                                                        GlyAsnProArgGlyValTyrLysValAspLeuThrIleProAsnLys                              505560                                                                        AspProArgCysGlnArgMetValAspGluIleValLysCysHisGlu                              65707580                                                                      GluAlaTyrAlaAlaAlaValGluGluTyrGluAlaAsnProProAla                              859095                                                                        ValAlaArgGlyLysLysProLeuLysProTyrGluGlyAspMetPro                              100105110                                                                     PhePheAspAsnGlyAspGlyThrThrThrPheLysPheLysCysTyr                              115120125                                                                     AlaSerPheGlnAspLysLysThrLysGluThrLysHisIleAsnLeu                              130135140                                                                     ValValValAspSerLysGlyLysLysMetGluAspValProIleIle                              145150155160                                                                  GlyGlyGlySerLysLeuLysValLysTyrSerLeuValProTyrLys                              165170175                                                                     TrpAsnThrAlaValGlyAlaSerValLysLeuGlnLeuGluSerVal                              180185190                                                                     MetLeuValGluLeuAlaThrPheGlyGlyGlyGluAspAspTrpAla                              195200205                                                                     AspGluValGluGluAsnGlyTyrValAlaSerGlySerAlaLysAla                              210215220                                                                     SerLysProArgAspGluGluSerTrpAspGluAspAspGluGluSer                              225230235240                                                                  GluGluAlaAspGluAspGlyAspPhe                                                   245                                                                           (2) INFORMATION FOR SEQ ID NO:33:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 23 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:33:                                      TTTTGCTAGCATGGGCTCCAGTG23                                                     (2) INFORMATION FOR SEQ ID NO:34:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 18 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:34:                                      GGCCCTTTCGTCTTCAAG18                                                          (2) INFORMATION FOR SEQ ID NO:35:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 36 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:35:                                      CCTACATATGGCTTCTATGACTGGTCACCACCACCA36                                        (2) INFORMATION FOR SEQ ID NO:36:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 53 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO:36:                                      CCCGGTCACCACCACCATCACCATGGTATGAGCGGCGGCATGGCTAAGAAGAT53                       (2) INFORMATION FOR SEQ ID NO:37:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 17 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: peptide                                                   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:37:                                      MetAlaSerMetThrGlyHisHisHisHisHisHisGlyMetSerGly                              151015                                                                        Gly                                                                           (2) INFORMATION FOR SEQ ID NO:38:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 4 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: peptide                                                   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:38:                                      MetSerGlyGly                                                                  (2) INFORMATION FOR SEQ ID NO:39:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 1158 base pairs                                                   (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: double                                                      (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: DNA (genomic)                                             (ix) FEATURE:                                                                 (A) NAME/KEY: CDS                                                             (B) LOCATION: 21..236                                                         (D) OTHER INFORMATION: /product="Ad12 pMu and pVI"                            (ix) FEATURE:                                                                 (A) NAME/KEY: CDS                                                             (B) LOCATION: 296..1090                                                       (D) OTHER INFORMATION: /product="Ad12 pMu and pVI"                            (xi) SEQUENCE DESCRIPTION: SEQ ID NO:39:                                      CTGCGCTGCCGTTTTTTCAGATGGCTCTTACTTGCCGAATGCGCATACCC50                          MetAlaLeuThrCysArgMetArgIlePro                                                1510                                                                          ATTCCAGGATACAGAGGACGACCCCGCCGGAGGAAAGGGCTGACCGGG98                            IleProGlyTyrArgGlyArgProArgArgArgLysGlyLeuThrGly                              152025                                                                        AACGGTCGATTTCGGCGGCGTAGTATGCGCAGACGCATGAAGGGTGGG146                           AsnGlyArgPheArgArgArgSerMetArgArgArgMetLysGlyGly                              303540                                                                        GTGCTGCCCTTCCTAATTCCACTTATTGCTGCGGCCATTGGAGCCGTT194                           ValLeuProPheLeuIleProLeuIleAlaAlaAlaIleGlyAlaVal                              455055                                                                        CCCGGAATTGCCTCAGTAGCCTTGCAGGCTTCTCGAAAAAAT236                                 ProGlyIleAlaSerValAlaLeuGlnAlaSerArgLysAsn                                    606570                                                                        TAAAATAAAATAAAACTTCCAACTTATTACTGGTACTATGACTGTTTTATGCAGACTAA295                ATGGAAGACATCAATTTTTCGTCGCTGGCCCCGCGACACGGCACGCGG343                           MetGluAspIleAsnPheSerSerLeuAlaProArgHisGlyThrArg                              151015                                                                        CCGTACATGGGCACCTGGAACGAGATCGGCACGAGCCAGCTGAACGGG391                           ProTyrMetGlyThrTrpAsnGluIleGlyThrSerGlnLeuAsnGly                              202530                                                                        GGCGCCTTCAATTGGAACAGTATCTGGAGCGGTCTTAAAAATTTTGGT439                           GlyAlaPheAsnTrpAsnSerIleTrpSerGlyLeuLysAsnPheGly                              354045                                                                        TCCACGATTAAGACATATGGCACCAAGGCGTGGAACAGCCAAACCGGC487                           SerThrIleLysThrTyrGlyThrLysAlaTrpAsnSerGlnThrGly                              505560                                                                        CAGATGCTAAGGGACAAGTTAAAAGACCAAAATTTTCAACAGAAAGTT535                           GlnMetLeuArgAspLysLeuLysAspGlnAsnPheGlnGlnLysVal                              65707580                                                                      GTAGATGGTCTGGCTTCGGGAATTAATGGAGTTGTAGACATAGCCAAT583                           ValAspGlyLeuAlaSerGlyIleAsnGlyValValAspIleAlaAsn                              859095                                                                        CAGGCTGTACAGAAAAAAATTGCCAACCGTTTAGAGCCGCGGCCCGAC631                           GlnAlaValGlnLysLysIleAlaAsnArgLeuGluProArgProAsp                              100105110                                                                     GAGGTAATGGTAGAGGAAAAGCTGCCACCTCTAGAAACTGTGCCCGGA679                           GluValMetValGluGluLysLeuProProLeuGluThrValProGly                              115120125                                                                     TCCGTTCCAACCAAAGGAGAAAAGCGGCCACGGCCGGATGCAGAGGAA727                           SerValProThrLysGlyGluLysArgProArgProAspAlaGluGlu                              130135140                                                                     ACCTTAGTAACGCACACAACAGAACCGCCGTCCTATGAGGAAGCAATA775                           ThrLeuValThrHisThrThrGluProProSerTyrGluGluAlaIle                              145150155160                                                                  AAACAAGGAGCCGCTCTGTCACCTACCACCTATCCCATGACCAAGCCT823                           LysGlnGlyAlaAlaLeuSerProThrThrTyrProMetThrLysPro                              165170175                                                                     ATTTTACCCATGGCTACTAGAGTGTATGGAAAAAACGAAAATGTGCCT871                           IleLeuProMetAlaThrArgValTyrGlyLysAsnGluAsnValPro                              180185190                                                                     ATGACCCTTGAGCTGCCTCCTTTGCCAGAACCCACTATCGCGGATCCC919                           MetThrLeuGluLeuProProLeuProGluProThrIleAlaAspPro                              195200205                                                                     GTAGGTTCCGTTCCTGTTGCATCTGTTCCAGTTGCATCGACAGTGAGC967                           ValGlySerValProValAlaSerValProValAlaSerThrValSer                              210215220                                                                     CGTCCAGCAGTGCGGCCTGTTGCCGTGGCTAGCTTGCGAAACCCACGA1015                          ArgProAlaValArgProValAlaValAlaSerLeuArgAsnProArg                              225230235240                                                                  TCCAGTAATTGGCAAAGTACCCTAAACAGTATTGTGGGACTGGGAGTA1063                          SerSerAsnTrpGlnSerThrLeuAsnSerIleValGlyLeuGlyVal                              245250255                                                                     AAGTCTCTCAAACGCCGACGCTGCTACTAACATTAAAAGACGAGTGT1110                           LysSerLeuLysArgArgArgCysTyr                                                   260265                                                                        TAATTCCCATCTGTGTATACGCCTCCTATGTTAGCGCCAGAGGACCAA1158                          (2) INFORMATION FOR SEQ ID NO:40:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 72 amino acids                                                    (B) TYPE: amino acid                                                          (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: protein                                                   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:40:                                      MetAlaLeuThrCysArgMetArgIleProIleProGlyTyrArgGly                              151015                                                                        ArgProArgArgArgLysGlyLeuThrGlyAsnGlyArgPheArgArg                              202530                                                                        ArgSerMetArgArgArgMetLysGlyGlyValLeuProPheLeuIle                              354045                                                                        ProLeuIleAlaAlaAlaIleGlyAlaValProGlyIleAlaSerVal                              505560                                                                        AlaLeuGlnAlaSerArgLysAsn                                                      6570                                                                          (2) INFORMATION FOR SEQ ID NO:41:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 265 amino acids                                                   (B) TYPE: amino acid                                                          (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: protein                                                   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:41:                                      MetGluAspIleAsnPheSerSerLeuAlaProArgHisGlyThrArg                              151015                                                                        ProTyrMetGlyThrTrpAsnGluIleGlyThrSerGlnLeuAsnGly                              202530                                                                        GlyAlaPheAsnTrpAsnSerIleTrpSerGlyLeuLysAsnPheGly                              354045                                                                        SerThrIleLysThrTyrGlyThrLysAlaTrpAsnSerGlnThrGly                              505560                                                                        GlnMetLeuArgAspLysLeuLysAspGlnAsnPheGlnGlnLysVal                              65707580                                                                      ValAspGlyLeuAlaSerGlyIleAsnGlyValValAspIleAlaAsn                              859095                                                                        GlnAlaValGlnLysLysIleAlaAsnArgLeuGluProArgProAsp                              100105110                                                                     GluValMetValGluGluLysLeuProProLeuGluThrValProGly                              115120125                                                                     SerValProThrLysGlyGluLysArgProArgProAspAlaGluGlu                              130135140                                                                     ThrLeuValThrHisThrThrGluProProSerTyrGluGluAlaIle                              145150155160                                                                  LysGlnGlyAlaAlaLeuSerProThrThrTyrProMetThrLysPro                              165170175                                                                     IleLeuProMetAlaThrArgValTyrGlyLysAsnGluAsnValPro                              180185190                                                                     MetThrLeuGluLeuProProLeuProGluProThrIleAlaAspPro                              195200205                                                                     ValGlySerValProValAlaSerValProValAlaSerThrValSer                              210215220                                                                     ArgProAlaValArgProValAlaValAlaSerLeuArgAsnProArg                              225230235240                                                                  SerSerAsnTrpGlnSerThrLeuAsnSerIleValGlyLeuGlyVal                              245250255                                                                     LysSerLeuLysArgArgArgCysTyr                                                   260265                                                                        (2) INFORMATION FOR SEQ ID NO:42:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 11 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: peptide                                                   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:42:                                      GlyValLysSerLeuLysArgArgArgCysTyr                                             1510                                                                          (2) INFORMATION FOR SEQ ID NO:43:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 11 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: peptide                                                   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:43:                                      GlyValGlnSerLeuLysArgArgArgCysPhe                                             1510                                                                          (2) INFORMATION FOR SEQ ID NO:44:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 5 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: peptide                                                   (ix) FEATURE:                                                                 (A) NAME/KEY: Peptide                                                         (B) LOCATION: 1..5                                                            (D) OTHER INFORMATION: /note="Xaa in position 1 is Leu,                       Ile or Met. Xaa in positions 2 and 5 is any amino acid."                      (xi) SEQUENCE DESCRIPTION: SEQ ID NO:44:                                      XaaXaaGlyGlyXaa                                                               15                                                                            (2) INFORMATION FOR SEQ ID NO:45:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 5 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS:                                                             (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: peptide                                                   (ix) FEATURE:                                                                 (A) NAME/KEY: Peptide                                                         (B) LOCATION: 1..5                                                            (D) OTHER INFORMATION: /note="Xaa in position 1 is Leu,                       Ile or Met. Xaa in positions 2 and 4 is any amino acid."                      (xi) SEQUENCE DESCRIPTION: SEQ ID NO:45:                                      XaaXaaGlyXaaGly                                                               15                                                                            __________________________________________________________________________

We claim:
 1. An isolated, activatable recombinant adenovirus proteinase.2. A recombinant adenovirus protein produced by host cells transformedwith a plasmid comprising a gene encoding an adenovirus proteinase orvariant thereof wherein the plasmid is selected from the groupconsisting of:a. pT7AD23K1; b. pT7AD23K2; c. pT7AD23K5; d. pT7AD23K6(ATCC Deposit No. 68322); e. pT7AD23K8; f. pT7AD23K10; g. pT7AD23K11; h.pT7AD23K13; i. pT7AD23K15; j. pT7AD23K16; and k. pT7AD23K18.
 3. Anisolated, activatable recombinant adenovirus proteinase made by:a.preparing a recombinant nucleic acid construct comprising a nucleic acidinsert encoding an adenovirus proteinase wherein the construct issuitable for expressing adenovirus proteinase in a host cell; b.introducing the construct into the host cell, thereby, obtaining a hostcell containing the construct; c. growing the host cell containing theconstruct under conditions suitable for expressing the adenovirusproteinase, thereby, producing host cells which express the recombinantproteinase; and d. isolating and purifying the recombinant adenovirusproteinase from the host cells.
 4. The isolated, activatable recombinantadenovirus proteinase of claim 3, wherein the construct is selected fromthe group of plasmids consisting of:a. pT7AD23K6; b. pT7AD23K8; c.pT7AD23K10; d. pT7AD23K13; and e. pT7AD23K16.
 5. An isolated,activatable recombinant adenovirus proteinase which is activated bycontacting the adenovirus proteinase with a polyanion cofactor ofadenovirus proteinase activity and a peptide cofactor of adenovirusproteinase activity.
 6. An isolated, activatable recombinant adenovirusproteinase which is activated by contacting the adenovirus proteinasewith a polyanion cofactor of adenovirus proteinase activity and apeptide cofactor of adenovirus proteinase activity, made by a methodcomprising the steps of:a. preparing a recombinant nucleic acidconstruct comprising a nucleic acid insert encoding an adenovirusproteinase wherein the construct is suitable for expressing adenovirusproteinase in a host cell; b. introducing the construct into the hostcell, thereby obtaining a host cell containing the construct; c. growingthe host cell containing the construct under conditions suitable forexpressing the adenovirus proteinase, thereby, producing host cellswhich express the recombinant proteinase; and d. isolating and purifyingthe recombinant adenovirus proteinase from the host cells.
 7. Anisolated, activatable recombinant adenovirus proteinase which isactivated by contacting the adenovirus proteinase with a polyanioncofactor of adenovirus proteinase activity and a peptide cofactor ofadenovirus proteinase activity, made by a method comprising the stepsof:a. introducing a nucleic acid construct which is suitable forexpressing adenovirus proteinase into a host cell, thereby obtaining ahost cell containing the construct; b. growing the host cell containingthe construct under conditions suitable for expressing the adenovirusproteinase, thereby producing host cells which express the recombinantproteinase; and c. isolating and purifying the recombinant adenovirusproteinase from the host cells.
 8. An isolated, activatable recombinantadenovirus proteinase which is activated by contacting the adenovirusproteinase with a polyanion cofactor of adenovirus proteinase activityand a peptide cofactor of adenovirus proteinase activity, made by amethod comprising the steps of:a. growing host cells containing anucleic acid construct which is suitable for expressing adenovirusproteinase, under conditions suitable for expressing the adenovirusproteinase; and b. isolating and purifying the recombinant adenovirusproteinase from the host cells.
 9. An isolated, activatable recombinantadenovirus proteinase having a molecular weight of approximately 22 kDato 26 kDa, which is activated by contacting the adenovirus proteinasewith a polyanion cofactor of adenovirus proteinase activity and apeptide cofactor of adenovirus proteinase activity.
 10. An isolated,activatable, recombinant adenovirus proteinase having the recognitionsequence X₁ X₂ GG|X₂ (SEQ ID NO:44) or X₁ X₂ GX₂ |G (SEQ ID NO:45),where X₁ is leucine, isoleucine or methionine, X₂ is any amino acid, Gis glycine, and a vertical line indicates a clevage site.
 11. A methodfor activating an isolated, activatable adenovirus proteinase comprisingcontacting the adenovirus proteinase with a polyanion cofactor ofadenovirus proteinase activity and a peptide cofactor of adenovirusproteinase activity.
 12. An isolated protein having the amino acidsequence SEQ ID NO:
 40. 13. An isolated protein having the amino acidsequence SEQ ID NO:
 41. 14. A variant of an adenovirus type 2 proteinasewhich has an additional cleavable carboxy-terminal peptide of about nineamino acid residues.
 15. A variant of an adenovirus type 2 proteinasewhich has an additional cleavable carboxy-terminal peptide of about nineamino acid residues, wherein the cleavable carboxy-terminal peptide isGly-His-His-His-His-His-His-Asn-Met (SEQ ID NO: 4).
 16. A reconstitutedpreparation of activated adenovirus proteinase, comprising:a. apurified, activatable recombinant adenovirus proteinase; b. a polyanioncofactor of adenovirus proteinase activity; and c. a peptide cofactor ofadenovirus proteinase activity.
 17. A preparation of claim 16, whereinthe polyanion cofactor is selected from the group consisting of:a. viralDNA; b. genomic DNA; c. oligonucleotides; d. RNA; e. polyaspartic acid;f. polyglutamic acid; and g. heparin.
 18. A preparation of claim 16,wherein the peptide cofactor of adenovirus proteinase activity is an 11amino acid peptide having the sequence: GVQSLKRRRCF (SEQ ID NO: 43). 19.A preparation of claim 16, wherein the peptide cofactor of adenovirusproteinase activity is an 11 amino acid peptide having the sequence:GVKSLKRRRCY (SEQ ID NO: 42).